http://goodmenproject.com/health/how-porn-can-ruin-your-sex-life-and-your-marriage/

Always young. Always beautiful. Always new. Porn keeps dopamine surging in the brain. But at what point does chronic stimulation become chronic dissatisfaction?

If you’re married and using Internet porn regularly, your sex life—the one with your wife—is probably a lot less satisfying than it could be.

You probably know that from an evolutionary standpoint, a man is rewarded for spreading his seed. But your wedding vows have an evolutionary purpose, too: they increase the chances that your joint offspring will have two caregivers, thus improving the odds that your genes will survive.

Internet porn, it turns out, messes with both these instincts. The endless variety and overstimulation may initially help you get more excited during sex, but over time it has the opposite effect: porn can dull your ability to please, and be pleased by, your partner.