I know this is by no means a new take (especially here on tumblr) but I'm of the very strong opinion that as written, the Acotar series actually provides a lot of evidence that most (if not all) of Rhysand's actions are in some shape or form always about Tamlin. Even his relationship with Feyre is about Tamlin.
A lot of people hold up Acomaf ch54 as this super romantic turning point for Rhys' character, which is incredibly funny to me because to me it only ever cemented the unfathomable levels of homoerotic obsession Rhysand has for Tamlin.
He admits that during Acotar he convinced Amarantha to let him go out of Utm to check on Tamlin and the Spring court, where he then left a decapitated head branded with the Night court symbol, like some weird bat shaped cat.
He also visits for Calamnai. (What are you doing here on the spring sex festival night, Rhysss?!? He isn't going to pick you!)
Obviously his meeting with Tamlin in Acotar is a classic for any Tamsand fan, his voice is a "lover's caress," he demands Tamlin call him Rhys instead of Rhysand for old times' sake (???!!), he threatenes Feyre‘s life to make Tamlin get on his knees and specifically fixates on her sexual thoughts about Tamlin.
When he kisses her utm to cover up Tamlin‘s scent, she also weirdly remarks on the fact that Rhysand can still taste Tamlin, which... is quite the odd thing to point out, if I'm meant to believe he is only interested in Feyre.
He also has literally admitted, to Feyre herself no less, that his weird roofy lapdance humiliation of her utm was specifically to upset Tamlin.
It just screams of "if I can't have you than I'm going to make your life miserable and steal your girl" behavior.
All his posturing in front of Feyre, presenting himself as the most powerful HL, the prettiest, the best and most just ruler, etc just comes across as him desperately trying to prove how much better he is than Tamlin, which obvs was intended to make him appear more attractive as the new love interest, but quite frankly it just seems kinda pathetic (I mean this affectionately, especially in the context of Tamsand. But eve beyond the ship, I just really adore pathetic fictional men).
Even in Acofas, he cannot stay away from the Spring court, he claims he needs to go there for diplomatic reasons, but he literally has courtiers? He has send both Cassian and Lucien on diplomatic missions before? Why would he personally need to go?
But, when he meets with Tamlin, he tells him that being with Feyre (his mate and supposedly love of his life?!) isn't enough, and he tries to goad Tamlin into a fight. (He wants to wrestle him so bad it makes him look stupid fr). When Tamlin doesn‘t respond like Rhysand hopes, he gets disappointed and dejected. Later, he returns and cooks Tamlin food, an action that has been explicitly romantically coded in this series...
Also, as a side note throughout that entire interaction, Rhys' internal monologue can't shut up about how green Tamlin‘s eyes are.
I'm hyper critical of the Acotar series and Sjm on the best of days, I don't like how Rhysand's character is written at all. But reading him as the most egregious case of a closeted gay guy channelling all his surpressed feelings into being the most toxic ex might be the only way his character writing can be redeemed for me personally (unfortunately Sjm is too much of a coward to ever purposefully write this).
I know its never gonna happen in canon, but to me the perfect resolution to the series would be Rhysand and Tamlin resolving their gay rivalry and finally getting together to live out their thruth as the disaster couple they were clearly meant to be. While Feyre and her sisters get to go off and be free from the clutches of all these toxic men.