My sim is engaged to no-one so her partner can't propose.

I'm trying  to get my sim engaged to her partner, but it's flagged her as already engaged. But she has no romantic relationship with any other sim, as her current partner is the only sim she's had a relationship. Neither of them can propose to each other because my female sim is the one who's apparently engaged. I've tried to clear all "marriages" in the Shift-Click menu and that didn't work. I tried looking with MC Command to see if it says anyone there, nothing. Can anyone help me with this, I'm a bit desperate.