amusedbush, if your care came under the Mental Health Act, you have made sure that each other can 'pull rank' and have a greater say in each others care.
My DH's Family have some very strange and ignorant views. When he had a brain tumour, if I hadn't have been able to overrule them (as first in-line, under the law, relative), things wouldn't have gone as well for him.
I know someone who had to fight to find out about the funeral arrangements of her DP, because his Mother had it done and dusted before she realised.
Marriage, legally is a formal separation of your other close relatives, as such and a declaration of the importance of your now, Spouse.
If your DP has Adult children, or questionable blood relatives, it's especially important. Unless you want them as your legal representative.
But getting married for love, is a valid reason. Do we have a Gay section? Gaining the right to marriage wasn't just about wanting things to be equal for many same sex relationships. For some different sex relationships it is, that's why a Civil Partnership was wanted.