Sims 3 Dating and Marriage Help?

Okay, so i have the sims 3

and there is a problem, my sims cannot date or get married if they have already been with someone else. And i know that whole thing that you have to wait until they have liked each other a lot. But they do, and the only thing they cannot do is date or get married. They can Woohoo...

Anyways, if anyone has run into this problem, or has fixed it. can you please tell me how to fix it.

Thanks.Sims 3 Dating and Marriage Help?
i had the same problem but i realised what the problem was it turns out my male sim (who moved in as a friend) was already in a relationship with someone else, what i did was looked in to the relationship section at the bottom of the screen, invited the girl round (it should say that he/she is in a relationship at the bottom of someones picture, if you keep looking you should find it) and i pressed mean %26gt; break up, now my two sims are happily married with a baby.

hope this helps

if none of them are in a realtionship or already married im guessing they are related in some way or there is a bug in your game