Final answer:
Regina and Juan, sharing personal information and having pet names, are likely in the 'romantic love' stage of their relationship, according to Sternberg's triangular theory of love, which is characterized by passion and intimacy but without long-term commitment. Option 3
Step-by-step explanation:
According to Sternberg's Triangular Theory of Love, the type of love defined by passion and intimacy but no commitment is known as romantic love. In the situation described, Regina and Juan are sharing personal information and have developed pet names for each other which indicates a level of intimacy.
They have been dating for a month, suggesting the presence of passion. However, since they have just dated for a month, there may not be a long-term commitment yet. Therefore, the stage they are in their relationship is likely the romantic love stage. Option 3