I think you need to decide if this is what you want - To break up then him coming back, then him again withdrawing and fooling with ex....?
He is Saturn, in his own sign and house, detriment of Moon. Its clear he is not really interested in you. Sun, which is his sexual side, in exaltation of Venus, so when he wants love and all that comes with it, he seeks it. So I'd say he desires you physically but not really interested in you as a person.
Saturn exalts Mars, that could be the ex, Mars is applying to Saturn, so I don't think its over between them. I think he might still have some interest in her based on reception.
Looking at this, he likes you both, you physically, her emotionally...at least what it comes across. He wants to have the cake and eat it too....
ball is in your court....
edit: Mars can be a new person too...as its an applying aspect, so could be that he is involved with several women.