What an absolute fucking treat he is!
He messes you about, probably picking you up whenever his flock of other girls is running dry or he's going through a phase where they're all ditching him having realised he's a weapons grade bell-end.
He finally shags himself into a corner where everyone he knows, knows everyone else, knows everyone he has screwed over and treated like shit, and it occurs to him there is a better option out there...
SO he comes running back to you, because he knows he can pick up where he left off, make out like he wants to settle down... and then you'll be there at home with several small children and he can carry on playing the field once he's shackled you to the house.
You've spoilt that by shagging someone he potentially knows, or who knows people he knows, and he CANNOT have that as it risks his two worlds colliding and fucking up his game plan.
So he drops you, and probably in a few weeks/months, will come trundling back with some conditions attached... once he's found out how many people know about this and how much it damages his ego.
Do not touch this man with a bargepole, not even someone elses bargepole.
He was never your 'partner', nor will he ever be, he has zero intentions of a relationship with you that in any way comes close to what you want from life with another person.
YOu will not be the one to 'change him' he does not want to change, he has no interest in doing that, he's more than happy with the way he is.