What is emotional betrayal and why is it dangerous?

Emotional cheating is when a person is married or in a serious relationship, but gives someone else more time, energy and feelings than their partner. With this "friend" he shares his innermost thoughts, he prefers to turn to him for support, warmth and emotional strokes. In other words, looking for emotions on the side. Such an emotional connection is also a kind of betrayal, albeit without sex. Because this "just friendship" over time can easily end in bed.