Jenny, I couldn't resist answering your call! That's a switch, since you are always the one that others lean on, including me. Maybe you can ask yourself a few questions. Such as: how did son do when H was picking up some of the slack? How does H do when you appeal to him to help out with challenges, as in I need your strength/wisdom/help in dealing with this? Does your leave of absence mean that you have to do away entirely with having some time to yourself, as in leisure time? Can you act as if your son is now your next "project" (I know bad choice of words, but you might see what I mean).
I've never dealt with ADD myself, though I do see some potential for it in my own son, now 8. Now that my h and I are doing better, he seems to be pouting/sulking/demanding more time, in spite of the fact that for the past two years I have been in some ways a bit of a ghost mom (mentally, not physically). Is it at all possible that your s is "creating" conflict where there's a vacuum, and if so, how does a professional such as yourself deal with that? Can you effect a seesaw/balance with your s, as in DB, so that you are doing less (or more) of one thing while he does the reverse? It sounds to me like you are the mom who rushes in to fix and save (like most of us here, to tell the truth); can you do a 180 and (while still on your leave of absence) do nothing? Sit back and watch? (Sorry, since I don't know the particulars, I can't give specific suggestions.) Is it at all possible there's a bit of a testosterone power struggle going on over your attention? Maybe h's dissatisfaction had to do with your attention on sons, and now maybe son is acting out your attention on h. Maybe you need to leave for a week (possibly take other son?) and let the two boys deal with each other? Is it possible you could send them on an outward bound thing together? Or a camping/fishing whatever trip together? Maybe they need to bond more closely, and so break some of the hold they have on you. Just my two cents.