Proposal got rejected with full relationship bars?

What are her traits? You said she wasn't noncommital, but there may be something. That or she was just not in the mood. I've had sims with a great relationship and flirting like crazy, tell them how you really feel (confess your attraction or whatever) and they act like you are stalking them! I find it easiest when this happens to move them in and then make them ask. It's my evil way of punishing them for breaking my sim's little heart!