Is it permissible for a woman to resort to masturbation if her husband reduces intercourse with her and does not satisfy her needs, especially with her fear of falling into the forbidden, and what is the legitimate alternative to that?

Allah Almighty has commanded the husband to treat his wife kindly. Not fulfilling his wife's desire for intercourse is not considered kind treatment. Therefore, the husband must have intercourse with his wife according to his ability and her desire. We advise the wife to pray that Allah reforms her husband, to continue speaking with him in a good manner, and to inform him of the words of scholars, in addition to beautifying herself and being a good wife. Masturbation is forbidden, and it is obligatory to avoid stimuli that arouse desire, and to strive for means that suppress desire, such as fasting, occupying one's time with what is beneficial, and associating with the righteous. Masturbation must be avoided, but if it becomes the only way to avoid falling into adultery, then we hope there is no harm in resorting to it out of necessity, and necessity is determined by its extent. Residing in lands of disbelief is a cause of many temptations, so migration is obligatory for anyone who fears temptation for himself.