Just don't understand

Someone explain this to me--my ADHD DH has been working literally 7 days a week from 6am until 10pm.  He has been unemployed since January so these are side jobs, handy man stuff that he is doing.  While I am happy at the money that is coming in and the fact that he is busy and has somewhere to go every day, our two kids miss him terribly.  He himself says how much he misses them.  Side note--he and I are on the verge of divorce, so I don't care when/if he's around, but the kids do.  Today he took a day off.  I took the kids out to meet a friend from out of town for a brief brunch--we left at 10am, were home by 11:30--I told DH when we would be home.  He was not home when we got home, no idea where he went and he is still not home--it's now 2pm.  The kids have asked me several times where he is. I told them I don't know.  One son texted Daddy to see where he was-no answer.  If you hadn't seen your kids in literally weeks and got a day off, wouldn't you want to spend time with them?  Especially when you yourself keep saying how much you miss them?  Forget me--I don't want to spend time with him anyway, but why not make a plan for you and the kids?  I just don't understand.  And I have called his attention to this kind of thing before and he guess what??  Blames me--well, I didn't know what your plans were or some such.  Really I think he just wants to avoid conflict with me at all costs, even at the cost of his relationship with his own kids.  I am very concerned that when we divorce he won't make much effort to see them.  Not that he doesn't care about them, but that it won't occur to him to make plans-out of sight out of mind kind of thing.  It's too bad because they are great boys and they miss their dad.  He isn't tuned in enough to see that.