There are many reasons why marriages become sexless. Intimacy anorexia happens more frequently than you might think. It’s when a spouse actively withholds spiritual, emotional, and sexual intimacy as a form of manipulation.
There is also sexual addiction; a spouse may partake in purchasing pornography or having sex with prostitutes. The spouse may suffer from the memory of being sexually abused, committed by an adult they once trusted or a stranger that preyed on them. Other psychological problems associated with a sexless marriage depression and schizoid personality disorder that will alienate the healthy spouse.
There's also physical problems, including a low thyroid gland, and, in men, low testosterone. There is also sexual miscommunication while having sex and just habitation sex can be an important factor as well. Not understanding your partner sexually makes the relationship rocky while routine frequency of intercourse tends to diminish over time, especially after 1–2 years of marriage. Medication may be applied to the physical problems, while therapy, singular and couple, can be applied to the mental and emotional problems.
There are different reasons why couples may have a sexless marriage. The most common reason is they lose attraction for each other. They just do not feel attracted to their partners anymore. Another reason is they are not excited about the sex anymore. They feel like they have already done everything and they do a routine anyway so there is nothing new to look forward to.
Some people do not want to have sex anymore because they have resentments towards their partners. They are somewhat angry and they are not able to express that yet. Another common reason is that the couple is sexually incompatible. Their sex drives are very much different from each other.