It's not you, it's me is a popular phrase used in the context of breaking up, and is intended to ease the person getting dump's feeling in the knowledge that it wasn't their fault, but rather the fault of the who's dumping.
I understand that at some sense it really is what they meant ''It's me'' but do they realise it doesn't give enough explanation? A lot ends it with just that phrase without explanation.
That's not enough, that's not closure. Every men/women deserves an explanation.