Depending on their age and sexual knowledge, you can explain that pornography has nothing to do with the reality of sex. Just as in the movies, where actors pretend to kill or pretend to feel emotions, professional actors pretend to have pleasure in pornographic images. Their movements are abrupt, and their poses are designed to allow the camera to show close-ups of certain body parts. Actors and actresses consume drugs to be more effective, and often undergo plastic surgery to change their bodies. Sometimes their body hair is shaved, and make-up and lighting are used to erase pimples, scars or natural skin colors. Pornography shows sex, not a loving sexual relationship.
In real life, it’s just the opposite: “making love” is tender, nice and soft. People talk, exchange hugs and kisses that bring both partners pleasure and well-being.