Borderline Bitter Husband

My husband is not taking being a stay at home dad very well. He’s disabled and our town is small so there’s been no opportunity for him. I worked from home, but a better opportunity presented itself so I recently started working out of the home. He’s happy for me, but isn’t taking being a stay at home dad very well. He’s been open and honest about his feelings which I’m grateful for, but how do I help him? I don’t want him becoming bitter or resentful towards me or our son or even himself. I know that’s out of my control, but there has to be something I can do, right? I feel so lost. What can I do? What can I say? Has anyone else’s SO ended up being a stay at home partner when they didn’t want to and have ended up feeling better about it? Any advice is appreciated.