Unscientific, but I think I remember reading somewhere that ~8 years was about the amount of time many people were able to deal with a shitty situation before they were psychologically done with it. I would also think after more and more time there is more sense of sunk cost and more to lose or fear of the unknown.

Not surprising about the Seals, or military members in general. The ones I saw that were most successful didn’t get married until they were already in for a while, and usually one of them was a veteran.