I’m sorry to hear that, that’s really hard. Accept an internet hug from us friendly strangers on Lemmy!

If you’re not too averse to Christian stuff, I highly and personally recommend www.themarriagecourse.org

It won’t probably help directly with coping with the MS, but can be really great for helping a lot of other areas of marriage, including your struggles with intimacy save romance. I recommend going in person if there’s one near enough.

Something like that can be great to do whether your marriage is on the rocks or going beautifully smoothly. - That might help your wife get over the sort of looming threat of “mental help for her”.

Anyway I’d second the advice of others that therapy can help. Don’t be afraid of finding you’re not suited for each other: Good marriage counselling is not just about “finding happiness with your own decision,” as another has said. Good marriage counselling helps you understand and rediscover each other and yourselves, giving you the best chance of (re)building relationship and new love with each other.

I can’t promise a cure-all solution, but I hope it can help.