I'm actually trying, currently. And, quite honestly, it's not working out so well. I dated my most recent exboyfriend for about a year. When I broke up with him he wanted to stay friends. Fine with me. So we did, and everything was cool. He took the break up like a champ and never said anything about it.
Then, about four months after our break up, I met my current boyfriend (who I am absolutely in love with). That's when things started to go south. At first, I had to convince current boyfriend that ex was just a friend. It took a couple months, but he finally grew to be okay with it. Then, ex saw that things were getting serious and started acting up in front of current boyfriend. My ex would grab my arm or follow me around or say he needed to talk and try to pull me off somewhere. Tensions grew. A LOT. To the point where they almost fought. I told ex he could either knock it off or we couldn't be friends. He did, but he still leaves current boyfriend on edge.
My ex and I have always gotten along, and he is a great friend. It would have been difficult to cut all ties with him when I broke up with him, but I really do think that would have been the best course of action. Now no one's happy and I'm stuck in the middle.