I masturbate often, and it's usually because I've become sexually stimulated by something and my partner isn't available or isn't in the mood.

I think that in most relationships one of the partners find themselves sexually stimulated from time to time when their partner is not. Masturbation provides a healthy outlet for that frustration.

Face it, even though we normally love the partner we are with everything isn't perfect, especially in the sex department. Rarely have I found a couple that have the exact same desires when it comes to sex.

Masturbation also provides us with an outlet for fantasies. So many people can't speak to their partners about their fantasies because they are afraid to rock the boat, being ashamed, think their fantasies are too far out, etc. Masturbation allows you to close your eyes and experience those fantasies, if only in your mind.