Far from using masturbation as a substitute for partner sex, most people find that that it piques one's appetite for partner sex. Woody Allen described masturbation as sex with someone you truly love. Like partner sex, masturbation involves genital fondling. But masturbation is fundamentally different from partner sex. Solo sex is its own special pleasure and shouldn't really be compared to partner sex.
Masturbation is just about everyone's original sexuality.
Men were masturbating long before they met their spouses. It's fun, fulfilling and relaxing. Some people believe that masturbation should not be necessary for people who are coupled, that each spouse should meet all of the other's sexual needs. But according to sex and relationship expert Pepper Schwartz, a professor of sociology at the University of Washington in Seattle, this view is naive. Spouses cannot meet each other's needs for the self-pleasuring they have enjoyed all their lives, which is by definition a solo activity.