you need to make sure that all of your stats are in the green. they can't be yellow. none
of them can be yellow.

I had the same problem, too. All you gotta do is sleep until your Sim thinks it's time to
go (best to use the sleeping mat on the beach by the conoe). If that doesn't work, then
fill up every motive up to green.

P.s. Girls Are Smart *_*

If you don't feel like waiting till your Sim wakes up(which is something I don't like to
wait for) then simply press R1, L1, down button, square and R2 to unlock Cheat
Gnome(pirate statue). Walk up to the statue then press R2, up button, X, square and L1 to
unlock "Fill all motives"(remember: you don't need to pause the game to do all this). Once
your done select the Cheat Gnome and select "Fill all motives" to get all your stats
green. Everything should go smoothly after all that. ;D