(it) (really) doesn't matter to me
I have no preference. A: "Where do you want to go to dinner?" B: "It doesn't matter to me. Any place you pick is fine." A: "You like the blue or the white paint better?" B: "Doesn't matter to me. It's your house, so you choose."
(It) (really) doesn't matter to me.
I do not care. Andrew: What shall I do? What shall I do? Alice: Do whatever you like. Jump off a bridge. Go live in the jungle. It really doesn't matter to me. Tom: I'm leaving you. Mary and I have decided that we're in love. Sue: So, go ahead. It doesn't matter to me. I don't care what you do.