Literally the same thoughts! I need these authors to be nuanced, because this is a real life situation people could go through and it teaches us the spectrum of sexuality. It's so boring to be black and white about it and just label him gay when clearly there's real feelings he had with his ex and crush. That's not how it works.
If we wanna get really nuanced I'd say he's probably biromantic not bisexual bc he doesn't seem sexually attracted to women. It could also just be that he thought he was interested in girls that way bc he was subconsciously trying to confirm to heteronormativity and didn't even consider the possibility he could be gay. Thats what happened to me as a lesbian who dated guys just because they were interested in me, which after some bad experiences I realized I'm not attracted to men like that.

Son you might not be gay but u aren't fully straight either son, u a bisexual or honestly u could be even be panromantic
And chat pls stop saying he's js gay ik it's pretty gay to kiss ur homie but it doesn't immediately erase that he also liked the blonde haired and also his ex romantically.
hope author dont make it some kind of plot device that he actually doesn't like girls only dated bcs of society, its just so boring? And super overused if u ask me.
same old excuses they do.
But still Overall you dont turn gay,lesbian,pan, etc.
You just discover stuff as life goes on.