This. The problem with porn is that it presents an extremely skewed view of sex, which can seriously interfere with a normal, healthy sex life. Most people don't look like porn stars, and many -- especially women -- have no interest in doing many of the acts commonly portrayed. Anal sex, for example, is a porn staple but something relatively few women have any interest in. Porn also presents sex as a casual and purely physical thing for the most part, which leads people -- especially but not exclusively young people -- to see casual hookups as a good thing, while in reality most people who pursue a lifestyle of casual sex find it to be unfulfilling. And then there are the dangers of unprotected sex, which porn also portrays and thereby encourages.
I've read stories of men who found that they had to close their eyes and envision their favorite porn star in order to climax with their girlfriend or wife. That is really, really sad, because it means that they're missing out on the deepest part of the sexual experience, the bonding with a life partner.
In a nutshell, porn can and often does ruin real sex, replacing it with a shallow imitation.