You might want to get him assessed for ADD/ADHD or something. I've recently been dx with ADD. It's not the end of the world. Symptoms can include an inability to concentrate on something for more long, inability to tidy up, time wasting, can't find things, can focus on things they enjoy to the exclusion of all others. It makes study difficult.
Even if it's not that - how could there be no issues if he feels his mother has rejected him? That would be devastating for any kid. Maybe some family therapy might help. Unfortunately, some counsellors are better than others. I've seen some bad/ineffective ones :( Your DH not disciplining him cos he feels he's been held to ransom re: returning to his Mum isn't going to work. This kid needs to feel loved and be the kid. His Dad can't be the needy kid too - IYKWIM?
And I agree with kirsty lee - your DH has to take the lead role on this, otherwise you're the evil stepmonster.
GL

