I do have some experience of the way your MIL is behaving. One of four siblings, three brothers, my DM, whom I loved beyond words, did have a problem adjusting to her children's adult choices. Three of us born on the cusp of WW2 in which my father served for six years. She was the centre of our world and a good caring and capable mother - no one could have had better.
Unfortunately, girlfriends and boyfriend were a very different issue and not welcomed and never quite good enough. It made life very, very difficult indeed because we loved her and wanted to please her. Her YS the only one to find his wife eventually accepted. My LH also finally accepted and whom she came to depend upon.
Sadly, she showed no interest in most of her grandchildren, and my D the only one of eight to have a relationship with her grandmother. All three of her sons deserted their M completely, and when she died she hadn't either seen or heard any thing from in years. The strange thing is when in her final weeks I asked if she wanted to see the boys her reply " No, I forget I have any sons - and I say that with no ill feeling toward either". I sincerely believe my mother would have been quite happy if neither of her children had married. They were simply, her children no matter the age and that is all she was interested in.
It would be lovely to tell you that in the end it all came together, sadly that is not my experience. And I think you may find it easier to leave well alone and get on with your own life. Invite her to join in when you can, and encourage your husband to see her, but do not expect any great change - that road likely to lead to disappointment.