The implication is that it is not mutual as it would be in a good friendship. Usually in this hypothetical the girl in question is herself being strung along by an emotionally unavailable boyfriend who treats her poorly but she is too attracted to him sexually to leave the relationship so she extracts the emotional support she expects from the boyfriend from beta orbiters. I don't think this scenario is nearly as common as simply a paralysis based on fear of rejection preventing someone from being forward about their feelings to the object of their affection.