I also have an H that didn't finish his journey, so I can relate to the double whammy from two BD's.
I tend to look at H as a teen who just landed in college and is making the best of a responsibility free life. You really can't do anything but wait for them to "grow up" again.
It's especially heartbreaking when you thought you had weathered the storm only to have it reverse course and come back stronger than before. I too spent a lot of time wondering how H could just walk away from a good life and a good family who loved him. But it goes with the territory of MLC land. It's hard to accept that there is nothing you can do but wait and be patient with the hope they will figure it out.
I think (at least my experience is) they put a lot of effort into making us believe that life is wonderful and it may be (for them) in the beginning ... like moving into his house. But, since they do take themselves with them, I don't think that euphoria lasts very long, although they won't let you know that!
The one concrete thing I can advise is to stop asking H about the (possible) OW. If there is something going on, he will just lie about it and whether there is or not, it's not good DBing. You can't detach and they can't see that you will be just fine with or without them if you're grilling them about OW or any other thing they might be doing. You have to zip your lips. Trust me, I know exactly how hard that is!
{{{Hugs}}}
2T2M
Me: 59 and holding H: :53 Me: 1 S, 1 D, both grown M: 19 T: 23 BD: 9-23-2013