I'll take it one step further and say that the more they do it, often times the more their betrayed spouse begins to pursue them . . . hard.
What made most of us come here in the first place? What woke us up from our lazy "I was a decent spouse, but nobody's picnic" marital mediocrity? Made us read self-help books, work out, lose weight, look better/dress better/smell better?
Our spouses cheated on us.
Strange dynamic, hunh? And yet, it's that "threat of loss" -- that pulling away -- that makes us pursue.
The key, young Grasshoppah, is to LEARN that most basic of human dynamics, and to FLIP IT to your advantage.