The bane of Null's existence is that he likes "andro-girls", in other words, slightly androgynous bisexual women. The reason for this attraction is to be found in his Italian genes: a lot of stunningly beautiful Italian women don't look
conventionally beautiful
by Western beauty standards, because they tend to have the strong and pronounced facial features that are associated with masculinity in the West, and hence those Italian women - who look perfectly beautiful and feminine by Italian standards - nevertheless appear somewhat androgynous by Western standards. It doesn't even have to be a conscious attraction towards androgyny in women, the fact is that that's what actually gets him off. Null can try to date more feminine or conventionally beautiful women, but the sexual spark just isn't there, and hence he can't climax when he's with those other women who don't meet his Italian beauty standards. Clara was bisexual, KFlay is too, some of the pictures Null posted of the women he was into when he was on 4chan, a lot of them looked slightly or more overtly androgynous. I really think that if Null was just a normal Italian boy who had grown up in Italy his whole life with Italian women around him, he never would've concluded that the type of women he likes are "andro". These women are only "andro" by Western beauty standards. They are perfectly beautiful and feminine in their own ethnic context.
I really do think Null's intense hatred of gay people goes back to that simple fact of his attraction to androgynous women who are bisexual. Null fears that any woman he falls in love with and assumes to be "superstraight" like himself, will in the end turn out to be not straight but also gay - which means she will always have the option of choosing to be either with Null, or with some chick. Now which way is any self-respecting bisexual woman gonna go...
Null basically doesn't want his bisexual girlfriends to have that "escape clause" where they have the choice to be with other women.
It's such a fucking dumb reason to hate gay people - if you fear your bisexual woman getting with other women so damn much, like,
just don't date bisexual women dude! - but there you go.