No he is an ex for a reason, that ship has sailed, move on.
Out of respect, you could ask him if its ok to date his friend though.
It defends. <br />
Your ex might say his comfortable with it, but seeing you guys together might make him feel uneasy, and it might jeopardize each others friendships. I would advise you to think very carefully because these things can get complicated...
Doing that would be opening a can of worms you won't like, I think. You should date guys who are not associated with your 'friend zone'.
Yes, I do. When you date inside the friend-zone, feelings can be easily hurt, even though no one is trying to do that.
As you said, you keep good relations, so if you like that boy, date him. It's about your happiness. But if that really bothers you, you can talk with your ex, or ask that boy to talk with him as long as they are bestfriends ;)