I can think of 3 solutions:
1. Go to the Disk Utility and verify your disk permissions and disk. If the Disk Utility finds any problem with your disk permissions, then click "Repair Disk Permissions". If there is something wrong with your disk, shut down your computer, and turn on your computer using Recovery HD. To do that, while your computer starts up, hold Command+D keys on your keyboard. The Disk Utility will show up and there repair your disk (once again, if there's something wrong with the disk itself.)
2. Delete all the cache files. Some files may be corrupted and deleting them will force the game re-create them. A link to tell you how to do that is here: https://help.ea.com/article/how-to-clear-your-cache-for-the-sims-3-on-a-mac
3. Update yout game using Super Patcher. A link to that is here: http://forum.thesims3.com/jforum/posts/list/549552.page
Make sure you READ EVERYTHING on the page to prevent your game from getting worse.
4. Sorry to say this, but you may need to uninstall The Sims 3 your Mac. I know, it doesn't sound nice at all, but it may resolve your issues. Again, it MAY or MAY NOT. You take the risk.
I hope any of the solutions helps and please keep me posted.
Good luck!
