The dialogue in the preceding short scene makes it clear that the Prince cuts the encounter short and runs off. And then the Wife sings "Is that all? Does he miss me? Was he suddenly getting bored with me?"
I disagree. I think that can also very easily be post-coital. She might prefer that he stay and cuddle and talk and do it again, etc - but for him it was just about the seduction and the physical sex, and then he's suddenly making excuses to get out of there.
In any case, it's very clear to me that Stephanie J. Block thinks they did have sex. (A bit of a pelvic thrust on "then a moment" late in the song.) Also, she's the first Baker's Wife I've seen that really seems very emotionally affected by the realization that she just cheated on her husband. She's very distraught at the end of the song. Interesting choice which makes a lot of sense to me.