Hello losing patience.
You knew that he was caring for his mother when you first started dating him so what is different now after a few years ?
Except you sound demanding also but you are not 91. Is ther a little jeaslousey there? Shame on you.
His mother raise him and put things on back burner alot of times for him, now it is his turn.
I give him thumbs up big time for not being selfish and putting his mother 1st. My mother lived with me
( 30 YEAR )TILL SHE WAS 91 AND " I GOT TIRED SOMETIMES " BECAUSE I AM HUMAN, WITH ALSO 4 KIDS TO RAISE ON MY OWN.
With no help from mom's other kids. When my children got older that also help their grandma till she pass and they and me were right there. I would give anything if i could just have another hour of waiting on my mom. I miss her so much and she passed in 1993.
If you get married & is no reason you cant ( except you ) i pray that you are nice to mom. You 2 go out by yourself, even if its just a walk, and get a sitter, you can get them for kids and elders if her mind and body is still ok for some things why would you want to put her in a nursing home ?
You are very lucky to have this man. & MOM

God bless and take care of mom with love 
Nanadee 