I Don't Get People

So I got a random angry email from a friend raging at me for friend zoning him. Buuuuuuuut he's always been a literal friend,knows I'm muslim obviously and knows we don't do the boyfriend thing. So I'm wondering if he's turned incel or just having a bad day? If he wanted to be more than just friends why not just SAY it? Not like we WOULD be a thing but why get angry over a situation you dont have to be in by just saying something?