The benefits of marriage are mostly back-related.
In this post-everything age, there are few things that my cis-male partner is capable of that I, as a cis-female, am not pPeeing standing up is an obvious exception, but not for want of trying). However, emancipated and empowered though I am, I still cannot zip myself up in back-open dresses, give myself lovely long shoulder massages, pop zits on my spine, or murder back-bleeding mosquitoes.
For all this and more, you, I and everybody else needs a live-in partner, gods bless them.
[Plus, of course, they make tea. All hail live-in partners! (Or minions, or slavishly devoted parents, or house-elves.)]