I also think the problem is emotional with H. Probably guilty feelings. I can see how you must wonder how H would want someone like ow. But as you say they are like sharks circling and smell the blood.
In my case I wondered the same. Also I wondered how H could not see that she saw him as a meal ticket. I suspect the ow in my case was a complete manipulator. I chalk it up to the H needing/wanting comfort, something he got from her that he was not getting in our R.
An interesting thing I read on the family.org website where the H talked about being under stress in the M and never having learned how his needs should be met while growing up he looked elsewhere for comfort.
This happened in my sitch, don't know that it would be true for you. I also think my H did not get a lot of his needs met growing up and looked to s@x etc. to comfort him.