Jessica Harper, MIA?

Jessica Harper has nearly top-billing in both the opening and closing credits of this movie, yet she is a pretty minor player in the first half of the movie, and all but disappears in the second half. This seems very strange: why would the writers clearly set up a budding romance between her and Mark Linn-Baker and then completely drop it toward the end?

Is it possible there was a post-production decision to chop her out of the movie in the final edit?