You kiss your hommie, Syb, with a big wet one. He seems too interested in it to enjoy it at the level it was intended. Of course, it makes sense. After all, he claims he isn't gay, but you specifically remember him telling you that he journeys down chocolate street from time to time. So, which is it? Is he straight, and just masturbates in a very gay way? Or he is gay and just too far in the closet to realize anything?
You yourself are comfortable with this answer. You are straight, but you'd be open to something if somebody asked and consented for it. That's why you're okay with this kiss. Nothing about is sexual, but your masculinity isn't too weak that one kiss with your best friend will shatter it.
Syb may look at this question and say that it's a false dichotomy. He'd probably say that he isn't necessarily straight, but he is further from gayness than he is from straightness. You think Mew Mew asked the question at one of your sleepovers and he came up with this strange word, "androgynosexual". You have no idea what it means, but he said it basically means "boobs". You tried looking it up online, but it doesn't seem to pop up anything when you look. Of course, you have a special SLUETHING EXTENSION or SEx, that brings up primary source documents so that you can effectively sus out any problem that you have. So, perhaps that word just hasn't been used frequently enough to be in legal discourse.
You want to respect his affirmation of who he is, as you do with Mew Mew and their affirmation of who she is. You and Suki are both cis and straight, if that means anything. Like sexual attraction to imaginary characters needs to be canonically fitting. I will not concede with the notion that feelings for my characters will only be platonic. I know the internet; I've seen how a new thing that somebody may like can turn into an abomination of proportions and exertions. How the most innocent, sweet, inoffensive character, who may in fact be canonically a child, can be turned into succubus or incubus, who's only desire is to fill and/or be filled.