I agree with a lot of what is said on here but we only have CreamTea's version and it could well be that the grandchildren are the straw that broke the camel's back. My husband doesn't find me looking after my grandchildren quite as enjoyable as I do and it did cause problems. When I got to the bottom of it, it wasn't jealousy. When our last child had grown up, my husband had paid for expensive carpets, sofas and oak furniture after we had an extension built. At the time I was rather surprised because we normally went cheap but pleased because I loved the stuff. When my grandchild is with us, being ASD, he often throws things unexpectedly and my husband was anxious that stuff would get ruined. So every time my husband huffed or left the room, spending most of his time upstairs, I thought he was jealous of my grandson or just being childish. My grandson screeches unexpectedly too and my husband is obviously sensitive to sound so that is awkward.
When I look back, he has always been the disciplinarian and trying to hush the kids. He's not a bad person, he's just had enough of parenting and says things like, "I thought we we'd done our share of this."
We had to have a serious discussion where I explained that his behaviour was hurtful and it was affecting how I felt about his as a person. He doesn't do ultimatums and neither do I as they can be destructive. If we get to something that is really important to us, we are honest about that, acknowledge that it could be a deal breaker if we can't compromise and then look to how we can overcome the problem. We now balance our day more. He does errands, goes to lunch with a friend, etc and if he doesn't have anything to do, I take our grandson to a play centre or swimming for half the day. It isn't quite problem free but it is much better than it was and I like my husband more for it.
IF your husband is nice most of the time, I urge you to find a way through it by acknowledging it isn't what he would choose to do but asking him for a way to compromise so you can both be less unhappy. If he can't/won't talk (some people find it difficult to negotiate in a relationship) write to him so he has time to reflect before responding. Gild the lily about how much he means to you but assertive about how much this issue means to you. Good luck.