So, I should probably preface this by saying I myself usually don't believe these types of comments when I see them on here, since there is often no way to prove them. So if anyone doesn't believe what I'm about to say that's fine.
Anyway, having said that... I actually know Nico and can confirm that he's indeed bi.
We have some mutual friends and have met at parties. We're not close friends by any means, but we've talked several times. He's a really nice guy, very easy to talk to. A bit goofy as well, which is cute. When I first met him I was sure he was gay. He was talking about musicals (though I'm not saying straight guys can't love musicals) and made an offhand comment about how attractive some male celebrity was so that's why I just presumed he was gay. I also felt like he was a bit flirty, but I had a boyfriend at the time so I didn't flirt back.
Then I saw him a couple of weeks later at another party and he was making out with some girl he was dating (not his current girlfriend, this was a while ago). So I thought to myself that he was probably straight and I misread the signs, or that he was bi. A mutual friend later confirmed that he was indeed bi.
All of his friends know, it's not a big deal. I haven't kept up with his dating history or anything (again, don't know him that well) but that same mutual friend once told me she had lunch with him and some guy he was dating at the time so he's definitely had a boyfriend in the past.