The most important decision here is for you. Do you trust a guy who is not even sure whom he wants to spend the rest of his life with? Do you love him? If you don't have trust in him, better give up. But if you are willing to sacrifice, then just give him another chance.

Threesome!

leave him.

Just left him because if he still has problems to choose between you and his ex-girlfriend and even if he choose you at least he will always keep thinking of her !! That's my point of view and if I were in ur place I'd look for someone who don't hesitate and who is sure about his love ;-p And good luck for you

Your question implies that if a boy chooses you, then that makes the decision for you and you don't have to decide. Instead of waiting for someone to choose you, you might want to take matters into your own hands. Make a list of attributes you like in someone (honesty, sincerity, wry humor, whatever makes you drawn to someone) and then look for these traits in the people you meet. That way you will be choosing for yourself.