Q : Is Hachiman gay ? I mean, he basically faps when he sees Totsuka, but his only reaction to Yui getting closer to him is annoyance, I know he should be generally disinterested in everything and his banter with Yukino is just the way those two talk, but TBH the more he talks about Totsuka(in a rather creepy way) and the more he shows general dislike towards the two main heroins actually makes him look like he is a closed homosexual, and not just a person who is afraid of making friends.

A :
Hachiman's behavior towards Totsuka is a crucial part of his character, so listen up.
Hachiman is definitely not gay. Actually, he's drooling over Totsuka precisely because he is not gay.
Let's take a look at Hachiman's past. Countless times, he had gotten the wrong idea that a girl might like him, countless times, he had fallen for a girl, countless times, he had been rejected in a cruel manner. Especially the "getting the wrong idea" part played a big role in his "I hate nice girls" monologue in episode 5, season 1.
If Hachiman started thinking about a girl in that same fashion as he does about Totsuka, he'd fall in love with her, confess and get rejected. Then that girl will avoid him. Again, he would be hurt. It's a pattern he's experienced over and over. Whenever romance enters his life, things don't end well.
But this cannot happen with Totsuka. Totsuka is a guy. No matter how many times Hachiman will look at his cute figure, no matter how many times he fantasizes about him, he will not develop actual romantic interest towards Totsuka. Therefore, he won't confess. Therefore, he won't get rejected. Drooling over Totsuka is a safe option for Hachiman.

If you have any more questions about any part of the series, feel free to ask. Understanding what the characters are doing and why they're doing it is important in order to enjoy this series in full. And that's sometimes tricky to figure out, so ask away.