Neglect Is Dangerous
When a spouse feels neglected and bored at home, he or she may seek excitement elsewhere. One of the chief ingredients in extra-marital affairs is the fresh interest that two people express in each other. Consequently, both become good listeners, and the competition is on again.
Too often people ignore those closest to them. With the "prize" secured, they don't think of maintaining the strength of their relationships in order to keep the competition at bay. Frequently they neglect their mates because they are selfish and it's the easiest thing to do. But they are still competitive for their mates, or at least they should be. If they do not focus on their mates, they leave the door wide open for others to come in and look around. They lose by default.
(Dennis & Barbara Rainey, Building Your Mate's Self-Esteem, pp. 142-143)