The statement that Dr McMurray indicates is a proponent of social exchange theory.
Explanation:
Dr McMurray states that the couples Katie and Rob do not perceive how much they are getting out of their relationship as to how much they are putting into it.
Social Exchange theory framed by George Homans states that social behavior is purely an exchange process. According to Homans, this theory is based on factors like costs and benefits of a relationship, the expectations and comparison levels, studying possible alternatives.
As per this theory, a relationship is positive if benefits outweigh costs and negative if costs outweigh benefits.
In a marital relationship, social exchange theory emphasizes a balance between the benefits or rewards that the married partners receive from their relationship and the costs that they had to incur for maintaining the relationship.