You know what? I hate being uninformed. I hate being taken off guard, made to wonder, made to worry. That is what H has done to me all summer. That is what your H is doing, making you wonder and worry instead of outright saying "I rented an apt today, in case you noticed the withdrawals". Kills me!
And yes, he is possibly getting his own place, which is good because of OW, but bad, because he is making plans to be away from home for a bit. Support him if he approaches you. Offer to help make it comfortable for your S, NOT for H!!! But do it for your S.
You have to protect yourself and he has basically cornered you by not giving you enough information to feel comfortable.