The author does mention sex. But there's more to a relationship than how great you are with your mate between the sheets. If you don't have things in common beyond the bedroom, a marriage won't have the depth it needs to grow and stay alive in stressful times.
All true, but like an automobile if you take a vital part away, it does not matter how perfect everything else is.
If we had a perfect way to measure love and relationships and marriage, we would have alot fewer books and articles.
100% correct. If sex is the only way a couple 'communicates' and shows love, the marriage is doomed.