People don’t seem to understand that beyond all the RP speculation and mental masturbation that fundamentally humans change over time and the novelty of things decay over time as well. Sure, you’ll have withering Rollo rolling in his grave rocking chair muttering, “hyperrrrrr-Gammmy!” every possible instance he can, but the situation is actually usually a lot more simple than that.

You cannot predict how your hypothetical wife/husband will change 1,5, or 10+ years from now. This is why so many people get screwed over in marriages. Their now wife/husband may have been an amazing person before the marriage, but now years later he/she is essentially a completely different person in their relation to you.

Fundamentally, marriage requires a lot of mutual sacrifice, and in modern society where people couldn’t be bothered to even remotely consider delayed gratification — it doesn’t seem like a viable goal for the general population. From what is known about our evolutionary biology and psychology, there is nothing to suggest we are a default pair-bonding species.