Not sure why he would change his mind. Almost certain Barca have tapped him up, and IF they have , I can understand the reason why he wants to leave.
He agreed a deal with City and was about to sign before changing his mind.
He's already done it once, there's a decent chance he might do it again. These things happen all the time. Look at De Gea, he was minutes away from moving to Madrid to be with his girlfriend, 6 years later he's still here because she moved over.