I’d like to actually discuss the problems I perceive with Yudkowsky‘s take for a moment, before everyone can go on with telling each other how crap his opinion is.
First, quantifying emotional states is hard, if not impossible at the moment. This could easily lead to misconceptions and misunderstandings, as it is not clear what x% “better” means.
Second, people probably don’t always want to live in constant fear of getting dumped by their partners. I mean, I get it, if you are in a relationship where you would leave your partner for someone else it’s definitely not a bad idea to be clear about that, but I don’t think that is the norm at all in relationships “even” apart from marriage. So his tweet about marriages being an agreement to ignore other options is not wrong itself, but he seems to lack the understanding that many relationships outside of marriage include this social contract as well.
Especially in a monogamous relationship, this view does not seem to make sense to me as it’s just a possibly emotionally hurtful way to tell your partner about your fear of commitment.