Quick Definition: The fear of getting hurt from expressing oneself in the most vulnerable way, usually through romantic love, although it can apply to other types of relationships as well.
Ideally, a healthy or reformed healthy individual has strong IQ as well as EQ. Emotional intelligence and strength comes from being able to express oneself fully, and still be able to open up to the potential for hurt and rejection as well as love and rewards. After a certain point in each romantic relationship, there will be a period of decisions whereby each person lets the other one into their inner, more intimate personalities. The rejection of these personalities can be painful, because it is not usually public or visible to everyone. For example, an intimate couple may share secrets of their past, or have a certain way they giggle in bed. These rejections can be painful because the person, if rejected, is experiencing rejection as if this was the rejection of his core ego.
Intimacy can bring with it other benefits, although a healthy fear can be good for those who may have pursued intimacy with wrong mates in the past. An abused girl, for example, will have a higher degree of fear than a girl who grew up in a healthy family. This is her psyche protecting her from potential abuse.
Ideally, a PUA has a abundance mentality, and does not fear intimacy. He may not want it, but he does not fear it and owns up to his feelings of they indeed exist. Sometimes it is hard to tell if a PUA is really fearing intimacy or his fear is of limited options, or not finding another girl like that. One of the ultimate purposes of learning game is to have option with women, so that this fear of intimacy does not arise, and if it does, it is not related to a fear of self rejection or never finding the “right” girl.
A lot of PUAs who get girls but are not in relationships may have a genuine fear of intimacy.