Because they’re dumb. Going through boot camp, you constantly heard “Don’t get married.” What do dudes do? Get married to the first girl they meet when they arrive at their duty station (after they buy a truck obviously). They then deploy, workup is three months, home for a few, then seven months in country. And meanwhile your wife is at home, you’ve known her for a cup of coffee, and she’s like “Shit, I don’t know how to be alone.”