I don't think it should be a problem if a companion goes after you, I mean, all you have to do is not accept their advances, right? I had everyone wanting my Tav. But in the end, I wanted was Shadowheart, so I spoke with her first. If you don't want any, is easy, just don't pick the more obvious dialogues that would lead to it, or just refuse them/leave if they made you feel uncomfortable. This is not uncommon irl as well.
