Your W makes zero sense to me. Back when my kids were little, and I was putting in my time being full-time mom and full-time volunteer, there would have been ZERO chance I would have released my kung-fu grip on H long enough for him to sneak off, much less willingly leave him! I needed his help too much for that. I keep looking at the age of your boys and wondering "what on earth?"
I understand that you're saying you guys were focused on other things, but something doesn't make sense for me, D. I'm curious - what do your family members think is going on? Have they come up with any interesting theories?
Your situation is a real puzzle...I completely understand why you're confused.