I wish I knew the answer to this myself. I recently just broke up with my boyfriend. It's funny cuz that clip from The Mexican (I'm assuming that was the movie) was oddly applicable to my situation. I love him dearly, and I know he loves me, but unlike the idealistic views of the character in that video, sometimes you do have to call it quits. It takes two people to make a relationship work, and when you're the only one willing to honestly work on things, at a certain point you have to know when it's no longer healthy.
For me what's always helped is surrounding myself with friends. And I'm sorry, this might sound bad, but rebounds always help. >.< Not sex necessarily, but just flirting and letting some guy flirt with you and reminding yourself that there are other great guys out there and you will fall in love again with someone even more suitable for you.