Actually...a woman who has no sex drive CAN turn that around. it's very uncommon for someone to truly be asexual. Very often it is a hormonal imbalance, or psychological issues (such as believing it's dirty).
The thing is...he's going to have to get her to understand what an important issue this is in this marriage. He's likely to have to figure out if living this way with her indefinitely is a deal breaker. If it is, then he needs to communicate that to her. For me I had to tell my husband, "I love you but I cannot continue to live this way...if we don't seek professional help...we will not have another anniversary."
It's not fun to have to take a firm stance like that, but it's often necessary to shake the person into reality, realizing how important this is to you and your marriage.
