McGrath, I suppose you didn't mention granting favors, but it's not the point. The idea that a boss as a general rule expects sexual favors is a little, well, it's not unheard of, it's an abuse of power that happens and should be reasonably guarded against, but it's not normal either. Bosses might also expect you to paint their house, mow their lawn, grant any sort of favors at all. You seem to have no interest in the question, except when it is clearly egregious, so there's no point going on about all the ways that it might not be.
It's not reasonable to expect normal people to always give up pursuing normal relationships, even if power is involved, just because some people are freaks.