The answer to the given question is because they find themselves not being rewarded for the relational skills that they value.
Relational skills are a group of skills that include communication, motivation, conflict resolution, and coaching. Although relational skills are crucial to influencing other people at work, often times when women exhibit these skills they are considered as a natural expression of their gender instead of skills that they have to refine and get better in, thus making these skills valued less when expressed in women.