Regarding the issue of wife masturbation, below is a fatwa issued by Sheikh Ahmad Kutty, an Islamic scholar,
In Islam, marriage is a partnership based on mutual rights and obligations. It is, therefore, important that both spouses try their best to be considerate and sensitive towards the needs and feelings of one another and do their best to satisfy each other within the bounds of Islam.
Sexual fulfillment is an important part of mutual obligations of husband and wife. A husband definitely needs to be aware of his duty towards his wife in this respect, and take it seriously. Just as a wife has a duty to satisfy her husband, he is also obligated to satisfy her.
Should a husband be suffering from a sexual dysfunction, he is required to seek professional advice in order for their marriage to be a happy one. If he cannot satisfy her through sexual intercourse, he is perfectly justified in satisfying her through other avenues; such as to masturbate her. if this is done by him, he is working within the perfect limits of Islam. The husband doing it on her is different from she is doing it on herself. A person masturbating on himself/herself is not allowed in Islam except in a dire necessity where one fears falling into adultery.
Marriage is intended in Islam so as to be a shield against haram. So being married, one should never be forced into this option.