Wife and I started dating when in our teens in high school. Dated for 6 years before we got married. Now married for 45 years. She's the one and only.
Do I feel like I've missed something? Not at all. Although our PIV sex has really slowed (post-menopause, her drive just isn't the same), she still gives great head and hand jobs frequently. I, like most(?) men, take matters into my own hands regularly to relieve my sexual tension.
Because we dated throughout high school and college and then married early (I was 23, she 21), I really never pursued anyone else. We both had full-time jobs right out of college and I was always in a management role where a 40-hour week was a fantasy -- 50-60 hours weekly was the norm. So, sex with each other was satisfying, convenient, and then frequent.
You add a couple of kids to the mix, long work hours continue, kids activities involve not only transportation but coaching, and who has time to chase pussy outside of marriage? And when you are getting sex within marriage, why jeopardize the relationship?
I'm regularly amazed at the number of partners some guys on here have had. I get the idea of dating different women before finding the right gal. I even understand alcohol or drug-fueled sex with someone you just met at the bar as the alcohol/drug impairment clearly can block good judgement. But having sex with 5, 10, 20 or more partners seems as though you're trying to reach some numbers goal. Whatever.
To each his own.