Below is a brief summary of some of the issues dealing with this subject. I hope it might help. This is one of those hot buttons on which there is a great deal of disagreement and what is given here by no means touches all the bases.
Summary: The Bible no where specifically forbids or denounces masturbation. It does, of course, denounce all forms of sexual impurity and fantasies that would involve adulterous relationships whether actual or mental. The problem with masturbation is that it not only can become habit forming and addictive, but men and women often engage in pornography and adulterous fantasies in order to reach a climax. Further, the difference in sex drive in a couple is often not the real problem or issue. It is rather a breakdown in the relationship and in an understanding of the role of sex in marriage as that which not only gives pleasure but expresses love, unity, and commitment to each other. Masturbation expresses the opposite unless done with the other partner. The husband may experience orgasm with his wife without actual intercourse. If away from his wife and he is experiencing strong sexual desire and he can have an organism by thinking about his wife, etc. then that could be appropriate.
More Detail: As mentioned, the Bible does not directly address the issue of masturbation or deliberate self-stimulation of the sexual organ to the point of orgasm. It does warn against all forms of self-indulgence, adultery of the mind, and fornication. One of the problems involved is that though God created sex for enjoyment and pleasure, it is to be confined to the marriage relationship because it is also designed to express love (not just sexual love), unity, and total commitment. Masturbation is an act of self-gratification rather than a part of giving gratification and pleasure to one’s partner. Here are a few of the dangers of masturbation that some have listed:
1. Psychic effects. Masturbation has a tendency to isolate its captives psychologically and socially. In masturbation, the person is focused on self-alone even though he or she usually is fantasizing about someone else at the same time.
2. Emotional deprivation. It is impossible for the one who is practicing this habit to experience the full extent of sex emotions. Therefore, in short-circuiting the emotions one can easily be removed from the world of reality.
3. Damaged sensibility. The habit of masturbation has a tendency in numbing the mechanism of the sexual organs if practiced excessively. This lessens the sensibility and thus detracts from normal sexual relations of married life.
4. Self-gratification. The emotional background of self-gratification is not the least bit healthy and usually militates against the home, wife and family because it is focused only on self.
5. Control of the mind. Along with the act of masturbation comes the fantasy of the mind. When practiced often, a pattern or cycle seems to become established within the individual’s mind. Thus, perversion has a tendency to control the mind and this in turn initiates the act. The real danger lies in the guilt that increases as the individual dwells in this world of fantasy.
Much more could be said, but this will give you a few things to think about. There are plenty of theologians and pastors, etc., that I am sure would disagree with my comments on this, but here are some things for consideration.