Get clear about this first, then get it on. Along with food, water and oxygen, we need sex, in large quantities, in recipes ranging from simple to spicy. Research shows that a vital sex life contributes 25 percent or more to the plus side of a relationship, says the author. If your sex life stinks, the other 75 percent of your relationship reeks. If your partner isn't hitting on you, you feel unattractive.
Irritation is all that rises.
Petty arguments explode. You start fantasizing about other people. You may take it further and actually have an affair. Or you might just up and leave. Without effort, however, monogamy can slide toward the pits.