Those who have sex the most, masturbate the most. So, the short answer is, it is OK to masturbate. The longer answer takes other factors into consideration. Some partners have different degrees of sexual drive. When one partner wants sex more than the other, masturbation is an acceptable and understandable alternative.
Some women are upset, even outraged, if they find their partners masturbating.
Masterbation is probably universal for females as well as males. It generally represents an indivudual's introduction to sexual pleasure and self love. In this day of AIDS, increased incidence of sexually transmitted diseases, solo sex is a safe outlet for the healthy sexual impulses. Couples devote much time, energy and resources raising their children. This leaves less opportunity to attend to individual and mutual needs.