From past experience, it is very difficult. Not on the guy's end, but the girl's.Captain said:
I had a 3 month relationship that ended with her wanting to be friends out of nowhere. She went from extremely loving to cold in a day. I was fine with her decision and we parted ways as "friends." Next night, I went out with my buddies (also friends of hers) and party as a single man. "Somehow" word got out that I had too much fun that night with a particular stranger. She was pissed!. Since we share friends, it was hard to avoid her. Every chance she gets, she would verbally attack me and ruin any event we would go to. She would block all my attempts of talking to any females in her range. B1tch went nuts. What I don't understand at the time was that she initiated the breakup, why did she care what I did with my life.
But these days, I understand crazy b1tch is crazy. They can't stand you having fun and having a great life without them. That is always there, so the lesson is to not have ex's in your life.
Of course there are exceptions, but that is too uncommon to risk it.