Sex also emotionally bonds men and women, more so with women it seems, but it strengthens the marriage when experienced regularly.
I agree with you there, metmom, although it depends on which woman, which man, and what their experiences have been.
If a woman and man have each other exclusively as erotic interests from the git-go, they will be biologically patterned on each other. (You could say "habituated" but that's probably not strong enough.) They develop actual physiological triggers set off by the Only Other one's literally unique body chemistry. Or so Ive read.
This process --- as I kinda understand it --- is intricate, and can be significantly undermined by premarital sex with anther partner, by promiscuity or (maybe even moreso) by porn. Porn can ruin men's ability to respond to/ bond with their wives. It destroys all those tendrils to unique attachment.
The same may be true of women's indulgence in romance novels, movies, videos, whether its "The Bridges of Madison County" or "50 Shades of Black-and-Blue --- oops, I meant Grey.
It's not just modern pop culture that intoxicates this way. A friend of mine was reading Flaubert's Madame Bovary and was struck that reading novels—--French stories of chivalry and Sir Walter Scott—---is what destroyed Emma Bovary. She could have been a contented wife bonded to her commonplace but kindhearted husband; instead, craving passion and dash and danger, elegance and ecstasy, she ends up pursuing other men and ruining all that could have been good in her life and others'.