UPDATE:
I Succeeded. But i had my male sim propose. Heres my theory for the reason:
The first two times i had my Male sim ask my Female sim to go steady and then had him propose to her immediately after, which she rejected both times.
The third time, however, I tried haveing my Female sim ask my Male sim to go steady, and then I had my Male sim propose to my Female sim. and she accepted! :)
So i guess "ask to go steady" and "proposing" with the same sim at once makes things awkward for the receiving sim somehow.
