INTJ guy I don't understand

Hey, fellow INTP there needing help with understanding your behaviours as I'm failing miserably. Love this type with all my heart, but sometimes y'all genuinely feel like mysteries to me

Met this guy online like a year ago, he was always saying how much he hated the game he was playing, for which I relentlessly mocked him while being just as rude as he was. Begun what seemed a hate/hate relationship, after me asking a few times to elaborate exactly what he hated, he started talking to me about it a lot

Even though he was unbearable most of the time, either fully ignoring any questions or talking to other people but paying no attention to me on purpose, (he said he ignored me 70% of the time but initiated all of our dialogues), he really did start discussing stuff with me and even asked my opinion or ideas on many things There was a time when he made a 46 page long google doc about why he hated this game and I read it and also discussed with him. We started talking so often, he started texting me while I was just there, not even saying anything to him. Seemed like i was the closest human being to him in that time. Hell, sometimes he was even really nice

And by really nice I mean being friendly, remembering the things I did or liked, using my jokes and even saying "good day or night <3" to me once. (I'm treasuring this memory forever, it was 100% "cries when the uwu is too strong" and it was also hilarious compared to everything else he did. I could mock him all I want, he made great points and also had great humor, could I really resist?)

The problem was and still is (I messaged him after a year of silence as he just lost any will to talk to me at some point. And he seemed to enjoy our talk a lot, saying that he did need to let out the thoughts and even showing interest in ranting about games while I wasn't there, multiple times told me he would like to know my opinion on something, straight up) that there are just random times in the middle of our discussions or after them when he just either stopped replying or became dry for no apparent reason

I've never seen something like this before and I'm genuinely confused (excuse me for this post, but he's genuinely FUN to talk to, arghhhhh!!!). I tried not to pressure him much or leave him alone to his thoughts in those moments but then he just never comes back with anything and I have to gently recover the contact. If I tried being more straightforward and initiative, he just closed off more. And the worst part is that he does show interest a lot and seems to enjoy it just as I do, but then just pulls out this move

At this point im just down bad to get any idea of what I could've done wrong or what could've happened to him to do this. I really can't do this alone man, intjs are cats I'm a 100% dog owner my whole life. Any thoughts? T_T