Doesn't have to be. There are other relationships where you will be cared for in old age, that are not romantic partners.

I took care of my grandmother for over a year until she died, for example. My aunt took care of my other grandmother and my grandfather. My brother and sister helped out my aunt with that grandfather.

Close friends, nieces and nephews, cousins, live in nurses…. if you end up in a nursing home with alone you’ve either outlived everyone, not taken care of your financial situation, or never built meaningful relationships with anyone. That last one is a choice.