It would not be better if he was always like that. You two were arguing about a casting decision in a movie; there's a lot of gray there, you're not likely to ever be able to conclude that one decision would be correct in that scenario. If he can't see the gray area in something so obviously gray, then he's going to have trouble letting any disagreement go with anyone - he'd fight with people about all sorts of stupid bullshit and truly, wholeheartedly believe he's correct about it. I'm going to assume that he's not doing that, because I don't think anyone could even get into a relationship with someone like that to begin with. So he must be able to see that it's not a black & white issue, in which case there's something else going on. You told him that it was a matter of opinion and that you'd like to agree to disagree, but that didn't sit right with him - he hasn't changed your opinion, so he can't let it go. If I were you, I'd ask him to 1) explicitly acknowledge that there's no right answer in the debate. If he can acknowledge the gray area, then 2) ask him why he's not okay with you having a different opinion than him on this. Since he's already acknowledged that there's a gray area, he'll have to admit that something else is going on - either it's about you, or it's about him, but you gotta know before shit gets weirder because it's not normal to be so butthurt about something so trivial. You also mentioned him expecting/demanding that you take interest in his activities, yet refusing to take interest in yours because he "has better taste" than you. Again this is entirely subjective and he is, in fact, being an asshole. Nobody has the same taste in everything, so he's not treating you as an equal. He is refusing to be at peace with the fact that you two have different tastes and opinions - the only reason things have gone well is because you've capitulated to him and because your tastes & opinions generally line up well anyway. You need to find out why he insists on forcing his tastes, his opinions, onto you without reciprocation; my fear is that he's doing it because he doesn't see you as a separate, equal member of the relationship.