In all honesty, I find the power relationship squick...strange. (Which is not to say I advocate it...just that I find it unsquicky.) To make a probably unhelpful analogy--Xander/Faith is physically a power imbalance; we know for a fact that she's capable of holding him down and having her way with him, if she wants. But as far as I know, most people are unsquicked by the earlier scene between the two in "The Zeppo". Likewise, legal status aside for the moment, the mere existence of a social power differential between two lovers leaves me unbothered; there would have to be something like orders given before I would be disturbed by it.

Can I see the difficulty from a legal standpoint? I suppose. But it's something that would never have occurred to me on my own.