This is what really gets me about life and relationships in general. Being quite cynical at the moment after coming out of a 3 year relationship where we were best friends and had discussed (at length) marriage, children and all sorts, probably doesnt help. The fact is that no matter what you do, how nice you are, if you do absolutely everything right, its ALWAYS up to the other person with whome you put all your trust and love in, as to how the relationship works out. You have no control over another person and people can seem to just change in the blink of an eye. Makes you wonder who they really were all this time?
Im really sorry for what you are going through, its tough but take it from me and countless other people, you will wake up tomorrow, you will continue to breath, and life will carry on. Life will get better too. Chin up.