Based on the way the story has been written, especially following season 4, I do believe mike is likely gay atp. But “It’s not my fault you don’t like girls” still makes sense as projection if Mike is bi because lots of closeted bi teens are confused about their feelings, especially in the 80s where terms like “bisexual” wouldn’t have been as readily accessible to kids from Hawkins, Indiana.

Simply the fact that Mike likes boys/Will could make him worried that he’s gay and cause him to hyperfixate on the concept of not liking girls more often, especially if his feelings for El were waning, or if his feelings for Will were overwhelming, even if he did in fact have a crush on El at the start of the show. Nothing says being a closeted bi teen like bouncing back and forth between “I can’t be gay, I like girls” and “Oh no, I like boys, am I gay?”

I think there’s a common misconception that the bi Mike view necessitates oversimplifying the story as “Mike used to be into El, and now he’s into Will.” That isn’t necessarily the case. A bi Mike reading can still involve internalized homophobia, projection, the heteronormative pressure to conform and date girls, repression, and most of the things we talk about here.

(I didn’t really wanna get involved in this, but I feel like this is important to add).