If we believe Asterion is telling the truth during the drinking game in Chapter 17, he has never fucked a guy (the question includes the caveat "without using a charm", but I'm pretty sure he has never had a charm), nor has he sucked a dick.
Now, there are some general implications about Asterion and Phroneos in the backstory vignettes, but as far as I know we don't know exactly what happened. That could have stayed platonic.
(Strictly speaking, we also don't know anything about any potential relationships with women.)