Just let it be. It's hard, trust me I know! My husband and I have yo-yoed with our weight together for years. When I started this journey he did it a bit with me but quickly gave up and I
begged him to stick with it. I was really, really annoying, actually.

He finally told me to stop and I dropped it.
Well, after over a year of losing and some pretty clear results he started calorie counting (not at all what I do) and running. He did great and has already lost 33lbs! He's at a plateau right now but it's more the struggle with getting back on plan after the holidays and travel. However, he's kept up the running throughout it all and has been able to maintain his loss even with the chaos.
For him it really was a few things that finally triggered his loss:
1. He saw that I was able to stick with it for a whole year and lose, i.e. it was possible.
2. He found the right method of weight loss for him. I've never been successful with calorie counting but it worked well for him.
3. We had easy access to a gym, something we didn't have before.
4. We had more childcare than we did before so time wasn't an issue either
5. He tagged along for a trip to my nutritionist and learned a few things (even if they weren't directed at him)
6. After starting exercising he was able to get off some of the medicine he was taking before, which was some great extra motivation!
In the end it was a perfect storm. Something I couldn't have planned. The best thing you can do for your husband is take care of yourself. Also, if you're the cook in the family, cook healthy meals and snacks. Beyond that it's up to him.