Their romantic partner offering lots of value in other ways. I’m skeptical of this one because female partners are typically notoriously high maintenance in money, attention, and emotional labor. Sure, she might be great in a lot of ways, but it’s hard for that to add up enough to outweigh the usual costs.
Assuming arguendo this is true: if you care primarily about sex, hiring sex workers is orders of magnitude more efficient than marriage. Therefor the existence of a given marriage is evidence both sides get something out of it besides sex.
Hank Green on the worst things about no longer having cancer:
During cancer you have a team of high status people actively working for your benefit. Suddenly, they are gone.
You are not actually done.
The cancer could return.
you have to monitor for the cancer’s return, so every weird thing your body does now feels threatening. This will never entirely go away.
You have made a bunch of cancer friends, some of whom are doing much worse than you.
The cancer and the treatment both leave a permanent mark on your body,
including permanent disability.
your you has gone through a one way transformation