I believe that sex is one of the ultimate ways of giving yourself to another. In marriage, you commit your love to your partner. In sex, you commit your body. So, a marriage is not complete if the couple is not having sex. You can't truly commit the entirety of you without committing your body, because until we die our body is a part of our sexuality; who we are. Also, you want to please your partner, and sex is often considered one of the primary examples of pleasure. In marriage you also agree to have openness for the coming of children. Sex is for procreation as well as for pleasure. Therefore, through sex, you are committing your body and also your future: a future with raising children.
In addition to the marriage ring (and marriage itself), sex is an excellent symbol of commitment.
“Sex Life of Robots” | Michael Sullivan
“Sex Life of Robots” | Michael Sullivan
English: Created by Phil Scoville on June 25, 2005...Sex, in itself and like marriage, is a commitment, a promise of eternal union with that one special person in your life. It is a promise of not only love, but your body, your soul, and your entire being.