yup. This happened with me, and i got really annoyed & confuzzled

hehehehe but then I figured out that they just have to either
A- improve their relationship to the Max
B- the one you want to propose to might have commitment issues (if so then just make them read the commitment issue book...whatever it's called

)
C- One is "going steady" with another sim- you'll need to make that sim break up with the other sim or just give up & move on...This is something I like to do that's called "Virtual Cheating"
One thing that gets quite...strange in this game is if the sim gets pregnant with your boyfriend's baby (if your playing as a girl, that is) and you break up with the guy...it's like real life, so if anyone tells you this game is NOT educational, just explain this to them
