I had that condition in the 2nd grade - just shortly after my dad died. Has this boy gone through trauma? What happened to his natural dad? Divorce, etc? Or is he a bit autistic, or something?

He may need therapy by a better therapist too.

I don't know entirely about divorce over such a thing, but that's your call. My wife is a smoker and is stinky all the time. I don't divorce her over the smell :-) I also live in a sexless marriage - since my wife had a hysterectomy a couple years ago. But I'm sticking with it - been through too much to do anything about it.

Get the right help for him and find out the root cause. It may be that the attention he gets from the pants is the only attention he gets - so he's trained himself to do it. Some kids, sadly, enjoy abuse because it's the only attention their parents pay them. Praise him for the time periods he doesn't do it - try to break him from it through praise rather than punishment. But punishment should be involved in some aspects of solving the problem.