It can happen to anyone. You find yourself attracted to a friend's ex. So many thoughts run through your head and there are so many things to consider. If it remains a simple crush, no problem. If the other person has feelings for you, too, and if you decide to pursue a relationship, nothing's quite so simple. Several things happen when you date your friend's ex, things that affect your friendship and your new relationship. Keeping them in mind might help things progress a bit more smoothly.