Why do you think John was so eager to initiate a break between him and Paul? I do genuinely think he found Yoko intriguing and all encompassing in those first years ( like he mostly believed he was in love), but the way Paul continued to haunt the rest of John’s life (and vice versa obviously) it leaves more questions of why an idealized love with Yoko still couldn’t heal a void within John.
drops head into my hands
This is the exact question fans have been going over for decades. We have a bunch of ideas and likely explanations but none of them really explain why Yoko specifically was so important to John that he would savage Paul in the break up, especially since he knew from the start that she wasn't a trustworthy person considering she stalked him for over a year.
Some things we know: John was tired of being a Beatle and wanted to get the hell out of there, and Yoko seemed strong enough to stand up to the aftermath of this decision. John was a heroin addict and Yoko was his dealer. John was seething/coping/malding because Paul couldn't instantly fix his depression and addictions so John felt justified in using Yoko as a pawn. John was tired of making his own decisions and wanted someone else to manage his details so he could keep microwaving his brain with drugs (search "the liver king" on Youtube to watch someone do this in real time in the modern era.) John was brain damaged from excessive LSD and other substances and couldn't make proper decisions anymore. John wanted a replacement mommy because he never processed Julia's death and the tangled mess that was his home life so he sought out an older woman who played into his Oedipus complex.
All of these things are true to one degree or another and yet none of them really explain why Yoko was John's specific choice to say "fuck you, I'll get my own Paul, one with a pussy and who will get naked in public with me."
The ultimate cause for John abandoning Paul in such a vindictive way, IMO, is that John was unable to accept Paul's most selfish feelings and desires. John thought that True Love Conquers All and that he could have some sort of explicitly gay relationship with Paul and that they could go off together as a couple. Paul was not enthused about this idea, especially in light of Brian's passing, and he wanted to have kids.
He looked at John's emotional issues and his addictions, looked at how John was treating Cynthia and his own flesh and blood son, and thought "fuck no, I'm not hitching my cart to that." Paul was ultimately exhausted by John's issues and didn't want to stack a gay romance on top of it. Especially since he himself is scared of being perceived as gay and knew the entire Beatles media empire is/was riding on the four of them presenting themselves as heterosexual.
Paul wants kids. Paul wants to get married. Paul wants a responsible and steady partner. Paul does not want to be a part of the gay community because the emotional burden of being gay lead to Brian having a mental breakdown that ended in an accidental OD.
And this stuff matters because, right or wrong, this is Paul's most base self. These are (some of) his real feelings and deepest fears. Whether they are rooted in reality or not, this is the darker side that he wants to keep hidden from others. This is important because Paul showed this side to two people: John and Linda. And he got two different reactions.
Linda: was unhappy at first and had to come to terms with Paul being in a passionate gay situationship for a decade before settling for her. Ultimately decided that she could extend her compassion to Paul and loved him enough to get pregnant and married. Saw more and more of Paul in their private life and still decided to keep loving him because she was able to accept his darkest aspects without judgment even if she didn't always understand it.
John: absolutely freaked the fuck out, reacted with rage and anguish, and most importantly rejected Paul's darkest self. He understood what he saw and hated it. Paul had lead him on and let him think there was a chance when Paul didn't have the guts to follow through, and wanted to keep John as a sidepiece because Paul was terrified of being gay and the baggage that came with it. So he lashed out in revenge and fury. He was not able to extend compassion to Paul because John didn't want to admit that he had similar fears regarding being in a gay relationship, what it implied about him personally, and the terrible consequences it could bring down on the band. John was not strong enough to take personal ownership of his personal feelings.
John's reliance on Yoko and the way he treated their relationship as a PR media campaign was, IMO, a reaction to Paul's fears about homosexuality and drug addiction and how they touched off similar fears in John about the same topics. Despite John's progressive outlook, he still suffered a lot of fear and self judgment about homosexuality. He tried to overcome it when he wanted to commit to Paul (however he presented this, overtly with an ultimatum or not at all by trying to carry on as usual) but when Paul rejected him, all of those insecurities and self judgment came rushing back without Brian there to shore up John's confidence.
That, ultimately, is the heart of the split IMO. This was a Jungian confrontation with the unconscious. John and Paul, both at a crossroads in their lives, looked at the fully unmasked faces of their darkest fears and desires for the first time in their lives. They realized that they were deeply in love with each other and that they wanted to be together more than anything. They also saw that they were each terrified that this would destroy their legacy and life's work: The Beatles. They realized they were scared of imprisonment. They were scared they couldn't have children together or that they would treat their kids terribly if they did. They feared being trapped in substance abuse issues for the rest of their lives if they remained Beatles. Sobriety in Rishikesh exposed how sick they were of being Beatles and how they couldn't stand each other or their bandmates and that these toxic feelings of burn out, resentment, betrayal, sadness, longing, and yes, love, threatened to destroy everything they had built since they were teenagers.
When confronted with the hideous and terrifying faces of their unconscious selves, they glimpsed their true selfish desires and fears. They ran away from each other because they couldn't bear the exposure as sobriety and the new spiritual setting of Rishikesh tore down the partitions they had built to live in their John&Paul bubble. Reality crashed into them relentlessly and they both sought safety in heterosexual relationships that could receive the stamp of approval from society.
Paul had always clung to the notion that he and John would continue on in some form after The Beatles ended. Even when their artistic preferences diverged and they stopped writing together and stopped living together on the road, Paul held on to this. Even as John slowly disintegrated and became less and less committed to being a Beatle, Paul held on to the belief that he and John would last forever and outlast everyone else as songwriters. But Rishikesh tore the veil from Paul's eyes, not because he received an ultimatum from John, but because he was sober for the first time in years. After getting a good look at John and how he had dwindled, rattled by the terrifying reality of Brian's death, Paul was horrified by the realization that he did not want to be with John. Not anymore; not like this; not with the way John was abandoning his son for the sake of drugs and a stranger while trying to ply Paul in the background. And so Paul fled in his fear, seeking out a woman, any woman, to shack up with and dig himself out of the quicksand pit that was John and his self-destructive behavior, which Paul linked to homosexuality in the prison of his mind.
John, despite his terror of abandonment and fears that he was a curse on his male intimates, trusted Paul deeply. He didn't think that Paul would abandon him. He didn't necessarily like abandoning Julian and Cynthia but he saw it as the inevitable next step in his life because no one was benefitting from the arrangement and he resented them bitterly. Brian's death and the passing of Alma Cogan meant that John was emotionally adrift with no one to rely on. He had no experience managing his own emotional problems and floundered. Going to India and experiencing sobriety gave him some clarity on what he wanted in life (in this interpretation, Paul and some form of exclusivity and monogamy) but that didn't alleviate his despair and depression the way he wanted it to. Seeking his new magical cure he sends out lifelines to two possibilities: Paul and Yoko. Paul rejected John for all of the above reasons, touching off a similar crisis of existential despair in John and striking directly at his greatest fear: that he would be abandoned by the person he loved most in all the world because there was something deeply wrong and destructive about homosexual love.
Yoko of course is an interesting specimen on her own but in this facet she was the same as Linda: she saw John's unvarnished darker self, his darkest fears and desires, and she didn't run. She was able to accept John completely and without judgment. Yoko was older and had already fought her way through her confrontation with her unconscious self. She was a liberated thinker who embraced the hidden side of her nature and channeled them into creating interactive art pieces, where the goal was to help the audience members tap into their unconscious selves and accept their shadow drives. That is why Yoko's art reflects duality (with the furniture set cut into halves, representing the inherent duality of human nature), mystery (the "people wearing bags" thing, the box containing wet pickles where you shoved your hand inside it to touch them, representing the unknowable and frightening inner self that lives in all of us), and the river of the unconscious self which looks terrifying but can actually buoy us into greater understanding if we turn off our minds, relax, and float downstream (this was the art exhibit where she used water and glass and beds as a theme.) Yoko is deeply in touch with her unconscious and encouraged John to reach out to his. That is why John responded to her art so strongly.
That being said: John and Paul were still very young. They didn't understand what they were seeing or feeling. They ran in terror to seek the only safety they knew: heterosexual marriages with children. Remember that Paul entertained dressing drag and appeared on American television wearing a pink suit and dancing after he married Linda. John explored cross dressing and an open relationship once he was married to Yoko. In many ways, John and Paul were able to explore and understand their queerness better in the framework of heterosexual marriage because it gave them a safety net that protected them from the judgment of society.
In light of all this, I believe that John's vindictiveness towards Paul and his insistence on the split was powered by the fury stirred up by Paul's betrayal. Not just that Paul left John for Linda, but that Paul revealed his unconscious self to John and exposed his deepest fears and desires. John was appalled and disgusted at the sheer depravity and cowardice on Paul's part. In John's mind, these feelings destroyed the validity of their love and romance, because if Paul really did contain these feelings of fear, disgust, homophobia, and self loathing, then that meant that Paul must not have truly loved John and their legacy. John thought that love meant never feeling fear or discomfort or worry. So he rejected Paul as he suffered feelings of disillusionment and the realization that he had sunk a decade of his life into a man who did not have the courage to let go of his negative feelings and love John fully and completely.
But what's more I think John was furious because Paul's weakness exposes John's weakness. He knew that these feelings existed inside himself as well; that is why he ran to another woman instead of trying to work things out with Paul. John was unable to take ownership of his feelings and projected them onto Paul, leading to him punishing Paul for revealing these horrible truths about them both. A common theme with John is that he couldn't reconcile the fact that two people could love each other but still not work things out, hence remaining fixated on May Pang and even Cynthia, wondering if their marriage could have worked out if they tried harder.
John was able to accept his queerness or at least reconcile it to some degree but he couldn't do the same with Paul. He couldn't reconcile Paul's love and affection with the fact that Paul tore down the veil between their conscious and unconscious selves, forcing them into a confrontation with their darkest fears and desires and how these fears and desires were at odds. They were terrified of homosexuality and all that implied and yet never stopped wanting to be together in every way possible.
That is the void Yoko could not heal, that is why John punished Paul so viciously, that is why Paul loomed over both of John's marriages. Only John could reconcile himself with John; and that is the only task John was too scared to carry out. Someone had to take the blame and since John was too egotistical and insecure to shoulder his share of the load, he placed it all on Paul instead, all so that John didn't have to take ownership of his feelings.
