Help me find this yaoi manga please :3

I don't have any pictures or anything besides a vague recollection of what happened in the first (?) couple of chapters. Essentially, there was some sort of s*x party(?) and a guy thinks he's getting it on with a girl because the person has longish hair and isn't really letting out their voice, then he finds out it was a guy. Has anyone read anything like this and if so, could you please give me the title? Thank you in advance（╹◡╹）