You people know that marriage is a social construct, right? Trace the origin of marriage and check out how other countries view it; broaden your horizons a bit.
Some people even have open marriages and don’t care about their spouse banging someone else. How folks view sex is highly individualistic. I love variety and the rapture of a man’s body. I’ve got no shame in saying it. Also, don’t watch Dr. Phil; he’s a moral zealot with biases of his own.