This is not about men who have lost some of their libido due to aging. This is more about men who are in the peak of their sexual lives and who have developed a sudden disinterest in sex. Sexual intercourse alone cannot sustain a marriage or a relationship, but the absence of sex can have a devastating effect on any relationship.
A woman may be confused by the lack of interest in being intimate, and may even begin to wonder if her partner is being unfaithful.