7 year old whose dad is deploying soon is DRIVING ME BATTY?!?!?

My son is 7, and normally well behaved. He has an occasional tantrum, but it is normally short lived and he apologizes afterwards. But now my husband is leaving for Afghanistan in two weeks. I think that must be the reason he has been so incredibly grumpy lately. He gets upset over everything - and not whiny upset, but angry. He yells at everyone in the house. He bullies his sister. And every time I think he's doing better and try to reward him for it, he throws a huge fit instead of being happy about it. He was supposed to be grounded this week. But since he was being so good today, I told him he could have 30 minutes outside - but no bike. That had to be earned back separately. He still had his scooter, his skateboard, his neighborhood friends, and an assortment of outdoor toys. Instead of being happy that he got out of his grounding early, he threw a fit over the fact that he couldn't ride his bike! He tells me he hates me several times a week, and it's really starting to get to me. I've tried being patient, since I'm fairly sure he just doesn't know how to deal with his dad leaving. I've tried rewarding good behavior. I've tried punishing bad behavior. I've tried talking to him about what is bothering him. Nothing has worked. I'm seriously starting to wonder if I should take him to a therapist or something! Any ideas what may help him cope with this a little better?