Mela
you seem to have a good understanding of the problem. And your husband can see intellectually that jealousy isn't helping, but feelings don't just disappear as we all know. they are there. So since he is intellectualizing, that will help.
THe other thing is the time thing.
I think that was the biggest gripe i had when DH was riding a lot and i was home with the kids. He could have been cycling with ugly dudes, it didn't matter. He was out on the bike and i was home stuck with chores (but i didn't want to ride at that point either)
look for used Tandems. Deals happen. I've seen them. Don't sell your car, you're going to want it in the winter