I'd really suggest finding a babysitter at least one of those nights each week. When your partner is stuck sitting at home on the nights you are on dates, then there can be too much free time to BE dwelling on it. That's why so many people suggest when your partner is on dates, that you go do a hobby, go out with friends, do something for YOURSELF to help keep your mind off of it if you're having jealousy or envy.
That's really great that he is willing to stay at home and babysit, but it really isn't fair for him to have to do it every single time, even if he is OK with it. I imagine he might worry he would sound like he was whining or complaining or trying to suggest you break up with your lover if he had the nerve to tell you that he didn't want to be at home and asked you to find other childcare sometimes.
I also think the way you tell him you don't want to discuss/compare them in bed..well the phrasing is so long and awkward that if somebody said that to me I would think they did prefer the other partner. I really would sit him down and say that it's different with each of them, nice with both of you, but you don't want to be discussing it because its not his business, and that you wouldn't discuss how he was in bed with your lover because you respect both of their privacy, and ask him not to bring it up again.
Happiness will never come to those who fail to appreciate what they already have.