Maybe because he doesn't want any one else to have you, talk to him.
Why would an ex ask you back out if he seems not to love you?
He probably wants a asset that goes through you; sex, money, or a place to stay and not have to work. This is not the only reason but where I live it is.
It's obvious, he wants you not your lovely beautiful body parts near his! Just that! In my opinion, unless I love a boy so madly, I wouldn't go near him if he left me and came asking for me! Those who love you, have your every tear as a diamond , and those who don't, they think it's rubbish! So your choice!