As NYS will tell you, things and feelings change every day, every week and every year... I believe that Walk Aways change their feelings for Left behinds (us) when their feelings for OP's change.
It does happen. Case in point: an online bud of mine had his ex walk away about a year and some months ago, take up with a prestigious OM. My friend did everything he could, he was impeccable with his efforts. Made his changes, but the sitch didn't change. He went ahead with his life all the same, and found someone much better for himself, he's so happy now, bless him! But now, even though she's still with the OM, his ex is calling him almost every day, expressing regrets, wants to talk. She realizes what an absolutely great guy he really is, and she probably understands now that the problems weren't all about him. He doesn't want her anymore though, he now realizes what is better for him. He's amazed at how his ex now appears to be going through all the emotions that he had gone through.
