It probably says a lot about me that I'd rather see characters be allowed to be together in a story and show them navigating the challenges life throws at them while trying to preserve and nurture their relationship, rather than be kept apart by random plot twists constantly. I did a medium distance relationship thing for years — just close enough that we could see each other on weekends, just far enough apart that it was only weekends and it was an all-or-nothing commitment to do so — and all the artificial separation does is put you in a holding pattern. You can't progress when you aren't allowed to be together: you're stuck in a holding pattern of constantly wanting that overdramatizes the faraway state of being together, like a real couple, that prevents you from seeing and working on the issues you're inevitably going to have when you are together.
So many stories end at the point where the couple finally gets to be together, as though that was the hardest part and the greatest challenge is now over. It gives me an ever-increasing amount of respect for OG Charmed showing Piper & Leo progress through dating to marriage, having children, going through marriage counseling, and ultimately overcoming it all to stay together and be a family. Sure, there was plenty of plotty separation BS in there, too, but all that does to my mind is confirm that you don't need to keep couples from marrying or having families and lives together to throw plotty wrenches in their plans of Happily Ever After. HEA's are not givens in real life, they don't have to be givens in fiction, but you can take a chance and show some of the interpersonal challenges to staying together to keep audiences on their toes, and they don't have to be artificial challenges like marauding demons or secret government agencies. Honestly, I feel like the audience is less likely to question it if it's a real relationship issue than Random Plot Twist #47 (but by all means, do throw Random Plot Twist #47 at them to exacerbate the situation, we love some good doubling down!)
I give Lucifer a pass on this because they've done a great job of making their characters genuinely seem like they aren't ready to be in a relationship with each other every time they get close and something gets in the way — every event that drives them apart again highlights a very good reason why they aren't ready, shows them working through it, together or separately, and they're closer when they come out the other side, all without ever letting you question whether they really love each other, or, if they love each other so much, why they aren't just past all these little things already. Beauty and the Beast does an okay job with this, in that every excuse the show throws at them to question their relationship highlights an issue one has, or the other, or they both have together that they need to work through, but sometimes these insecurities do seem to come out of nowhere, or the thing that causes them to rethink things is random paranoia that had very little reason not to exist the episode before, or my personal favorite: Vincent did a thing that was Not Careful (tm) and gave himself away to someone, and now he's convinced himself that he can't have nice things after all, and is trying to convince Cat of the same. Sometimes Vincent doesn't have to convince anyone, because he is actually in trouble and physically incapable of having a single nice thing for a time. I take a lot of issue with these particular turns of events only because the show seems to contradict itself by introducing him to us as Mr. Paranoia, the legally dead man who lived outside society and without detection for ten years before he officially met Cat, who will only rendezvous with her on rooftops and in sewers, but then he will randomly decide that he can walk around a crowded street in broad daylight with his face uncovered, or that fire escapes take too long so he'll just jump down from five floors up when people are still awake and there's still traffic on the street below. I try to rationalize it away with the reasoning that he knows how to be careful, but he must at heart sometimes be an impetuous person, otherwise he wouldn't have ditched a career as a doctor to enlist in the army in a fit of anger and grief, let alone signed up for a medical experiment that he didn't question, nevermind go out and play vigilante when he should be a shut-in keeping his head down. They do try to paint a picture of pre-Beast!Vinny as a normal, mischievous, rambunctious guy, and I should give them kudos for that for rounding his character out instead of leaving him a perpetual unrealistic angst-monster with no other history or ties, but sometimes I wish more characters would question each other or call each other out for doing things that are blatantly unwise — or at least rant about each other to others when they're dumb — because it breaks immersion to question why someone suddenly goes against character so completely, even if it's something a normal human might do because the way Vincent has to live is not natural unless you're in a pandemic maybe. Lucifer may have made their titular character inconsistency-proof by writing him expressly to be flighty and spontaneous, but they still go the extra mile to have Chloe get mad at him, rant to other people about him, and try to figure him out when he's baffling, rather than just presenting him as baffling, shrugging, and letting it drive the action of the next 2-3 episodes without examining the crap out of it.
Of course all of this has nothing to do with the fact that I was completely ready for Catherine & Vincent to commit to taking a leap together and leaving their old lives behind, meeting new challenges of starting new lives head-on, seeing if their relationship actually holds up once there's nothing keeping them apart, and what they do with the fact that they left everything they had for each other whenever they hit a major bump and rethink things, rather than Plot intervening once again. Nope, nothing at all.