I have. I was with my ex fiancee for 7 years and we were best friends. Oddly enough that friendship continued even after we broke up and he continued his relationship with the girl he cheated on me with. I ultimately became friends with her as well and will be one of her bridesmaids wedding next spring. I realized that sometimes you come to the recollection that he was a better friend than a life partner.
Tried. Didn't work.
Happened both ways.
Tried to be friends but feeling arose and bad things happened. And it was better to get away from each other.