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!

Are you sure one of them isn't already married or engaged?
Also I've never tried this on a date, try at the house?

Just my random thoughts, I've never had a refusal.

I've had successful proposals on dates, so I don't think it's that.

Most of my proposals have been successful, but I've had a couple of rejections that surprised me as well. I've wondered if maybe the Sim I wasn't controlling was hungry or needed to go to the bathroom or something.

Neither of them are married or engaged to someone else because i made them both. Here are their traits:

the male sim:
1. Loves outdoors
2. Perfectionist
3. Good
Aspiration trait: Domestic

the female sim:
1. Music lover
2. Creative
3. Good
Aspiration trait: Domestic

and the funny thing was, after the rejection i quit without saving and loaded back to just after their first kiss. I had them go steady successfully and then I had him propose to her (again for me). To which she promptly rejected. is it a random thing or am i doing something wrong?

Do both your Sims live in the same household or is the female Sim not in your household? The only thing I can think of is maybe she's in a bad mood (like others have said) and you could move her into your household and make sure she's in a good mood before trying again.

If she already lives with your Sim...I'm really not sure? Does she have any bad moodlets at the time of the proposal? Maybe try having her propose to him (if you want).

Welcome to the fact tht traits don't affect it too much but have some impact.
Lol first you need minimums of 1/2 filled friendship bar and 3/4 filled romance bar
Then put them both in a happy mood, get the conversation flowing till the bar says steamy exchange or something above it.
Then have a sim propose, it doesn't matter which sim does it.
Since you've only tried your male sim, the issue may lie there. Try getting your female sim to propose. Sometimes the issue is with a particular sim. Things become too orquad if they're not kinda good friends or certain 'bad' sims are around. The 'bad' sims I'm talking about are some tht instantly make things too orquad without being active. You don't wanna rush the proposal.

ok. I'm going to have my male sim propose for a 3rd time. you know what they say, "third times the charm". But if that doesn't work i'll have my female sim propose.

Just keep at her, she'll give in!

http://media.giphy.com/media/rqe0ChW2iIFAA/giphy.gif

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.

Reminds me of my Sims 2 game the other week. My sims were engaged, they seemed perfectly in love, no problems, no cheating then it was time for the exchange of vows at the wedding and the groom rejected my poor sim... lol. I wanted to drown him in the pool I was so mad.

Anyway, idk why that happened, perhaps the game just has the chance (well I guess obviously) to make them reject the engagement. Perhaps you can try again?

Edit: Just read that you wrote you're going for the third time... Idk what is going on there. Did either of them ever have the non-committal trait? Because (idk if it's been fixed) but before if you changed the traits sims would still get moodlets from old traits or even just act like they still had the deleted trait(s).

Edit 2: Okay apparently my post was way late, just read the one above mine. Glad to hear you got it working lol.