Saito-san is probably bisexual and probably open about it given that his wife guessed that Tomita was his lover. Stories like this are so silly to me because y'all already had sex and are dating, yet labels are what keep you from literally just talking to each other? Tomita cares enough to cry, but refused to communicate any of his feelings to Saito. Big facepalm.
He doesn't know that Saito is a player, he only knows that he was once a host. He doesn't know much about Saito, a fact that he acknowledges is his fault. Tomito is jumping to his own conclusions about Saito (just like how he originally assumed Saito was gay and was interested in his coworker)... Yet in chapter 3, he's getting cold feet over how Saito isn't gay now?
Hmmm maybe you are right... Maybe Tomita is making up all these assumptions and putting all these excuses to run way since he has never been on the vulnerable side of a relationship, being a player before himself... I can relate to him feeling scared of getting hurt and would rather pull way before that ever happening and trying his best to just enjoy the ride before it gets too serious... But maybe he doest know yet how much he likes Saito and how deep in the relationship he is... Who knows ╮( ̄▽ ̄)╭

Interesting. I don’t think I’ve ever seen a manga where neither party identified as gay (most likely both are bisexual, but had never done anything with a man before.) Usually the gay party will pursue the “straight” guy, rarely(or maybe never) have I seen a straight character go after a gay character from the beginning.