Having had the same thing happen to me, my advice may be somewhat jaded and cold. My gf at the time came back to me after a fling, and I took her in. While i tried to let things go, there was always that lingering thought in the back of my head when she was out with the girls. While on the surface our relationship was fine, it was the feelings of mistrust and anger that that i had that ended the relationship. THe lesson i learned is that once the trust is broken in a relationship, it cannot be regained, as the heartbreak will always be there.I still have bad memories of it, in the extremly rare time i think of her. We parted ways, and I went out guiding in bush alaska to find myself. Untill one does that, there is no way to know what will make you happy. I learned a lot out on my own, and when i did meet my future wife, not only did i know when i saw her, i knew what i wnated out of it. But everyone will make their own decisions in life, so take all the wonderful advice that you have gotten, and when you make your decision, make the decision for YOUR HAPPINESS. Sounds selfish, but if you are not happy, there is no way you can make your special someone happy.

Jeff