How can we decide what's best for my parents who want to live together but are happier living separately in assisted living and a nursing home?

My mother in law is in an assisted living facility and loves the fact that there are so many activities, etc. and that some of her friends have recently moved in and that her church pays her a visit. My father in law was there for a short while but his incontinence problems prevented him from staying longer as it is not a skilled facility but an assisted living home. His roommate passed away recently and he would like his wife to join him in the Adult Foster Care. She is not interested in coming as he has no desire to participate in activities, etc. and sleeps most of the day and they do not offer as much. They do miss being together which makes this such a difficult decision. We want them both to be happy. Yes, it would be cheaper for them both to be together and easier on my brother-in-law and family to visit one facility instead of two. We are torn as to what is best for them both. My Mother in Law has been happy at the assisted living facility since day One. While he was there, he didn't participate much. Such a dilemma!