Would you become suspicious if your husband has not had sex with you in 2 years?

I have a friend who states that he husband has absolutely no desire in having sex. They have been married for 37 years. He has a drinking problem and gets drunk to the point where he falls downstairs. I have asked him to get help but he always says he does not have a drinking problem. But, sex does not exist in our marriage anymore and it's been that way for the past 2 years. I am open for suggestions.