The answer to the question relates to the concept of primary and secondary group. Primary group is a small social group where members share personal relationships that are generally enduring while secondary groups are large groups where relationships are temporary, impersonal, and goal-oriented.
The relationship between Monique and Zhong start off as members of a secondary group, which is their company. When they met in a company party and eventually dated each other, they become members of a primary group, which is a couple.
