He actively encourages them to love and cherish one another too, it's not like they're sneaking around. I'd be fairly surprised if any of the girls were less than a two on the Kinsey Scale.At first I was questioning why everyone saying that meme was bi (I won't deny it but I was still a lil confused) but now I'm thinking... If your boyfriend is dating like 46 other women he just can't satisfy your individual needs even if he is the reality bending rentarou, so ya gotta get some from somewhere might as well be his other girlfriends that's about as loyal as you can be with this situation.
Rentarou previously seemed to be a 0, in the first chapters. Now though, he is hypothetically capable of being up to a 3. He's oriented towards his lovers and would never feel less attracted to any of them even if, for example, Kusuri were to develop a drug that turned them all into boys (or, more masculine anyways). Or one of them realized they were actually a man (statistically likely in a pool of 100 to have one, but that's absolutely not happening in this story lmao). It's just that the title is 100 Girlfriends, so we're never going to see Rentarou zing on a guy. Like, there's no way.
Thus, Rentarou is effectively a 0, but it's like a Schrödinger's 0. Or you could say a 1, but the incident in which he would be in a homosexual relationship will never appear.