Proposal got rejected with full relationship bars?

Did your sim complain about their “fear of commitment” prior to the proposal? In my legacy family I had a sim reject twice once with full bars and my theory is it’s because of that interaction (I’ve had noncommittal sims with lower bars have no problems they just never used that interaction). You have to watch them like a hawk because NC sims can do that autonomously. So either keep them completely apart until right before the proposal or try switching up who is doing the asking.

It took me three tries but I did eventually get my sims engaged lol.