Dreams involving romantic interests and social situations often reflect your feelings about relationships and self-identity. In your dream, the AirBnB represents a temporary space, possibly indicating a transitional phase in your life or experimenting with new relationships.

Hooking up with the girl you liked, then shifting your focus to others, may symbolize feelings of desire and the confusion that can come with attraction. The regret you felt after being with the "fat one" could suggest underlying insecurities or concerns about your choices and how they align with your true desires.

Your best friend's disappointment might indicate your own internal conflict about the situation, suggesting you value his opinion and may feel pressured to meet certain expectations. Your brother's comment about the first girl being the coolest could reflect a desire for deeper connection or recognition of your true feelings.

Overall, this dream may be urging you to reflect on what you truly want in your relationships and to consider how your actions align with your values. It might be beneficial to explore your feelings for the first girl more deeply and think about what qualities you truly value in a partner.