Selina/Catwoman has a place in Batman's life because he's Batman. If Wayne retires Batman for good and leaves it behind, he leaves her behind. She's not going to suddenly start anew, not be a thief/outlaw any more and do the domestic thing as the wife of billionaire Bruce Wayne....and they 'need eachother' AS outlaws/vigilante's, not outside of it...the 'broken' part is what they share, not the healing part. They're enablers for each other but once the behavior is dropped, then there's nothing to really connect them, except a very brief past (in this story) which at least one is leaving behind for good.
If Miranda isn't Talia, she's a much more sensible choice. I know the comic-fan would like to see Bats and Cats tie the knot or what have you, but this really doesn't seem that kind of story.