Your dream seems to carry several layers of meaning, reflecting your current feelings and experiences in life, especially related to your social environment and personal challenges.

1. Library and Mirrors: Libraries often symbolize knowledge and learning, which aligns with your university setting. The mirrors could represent self-reflection or how you perceive yourself and how others perceive you. The annoyance from your friend may indicate feelings of rejection or misunderstanding in your social circles.
2. Changing Scenery: The transition from the library to a fair could signify a shift from a more structured and academic environment to one that feels chaotic and unwelcoming. The presence of people from your hometown might indicate unresolved feelings or conflicts with your past.
3. Friendships and Disappearance: Your friends' disappearing act could suggest feelings of isolation or the fear of losing connections. Your interaction with Marissa might reflect your desire for support and companionship, yet her sudden transformation could hint at confusion or a lack of clarity in your relationships.
4. Swing and Falling: Swinging with your friend represents joy and freedom, but falling and laughing might indicate a sense of resilience in the face of challenges. It shows that you can laugh off minor setbacks, which is a positive trait.
5. Spiders and Webs: The spiders and webs symbolize feelings of entrapment or anxiety. The fact that you are struggling to navigate through them could reflect obstacles in your life that seem daunting. Being short and having your dress get in the way might represent feeling unprepared or restricted in your ability to confront these challenges.
6. Fight and Escape: The fight breaking out might symbolize conflict in your life, while your desire to walk away suggests a need to avoid negativity or drama. The trucks and webs could represent feeling stuck between a hard place and a rock, especially in terms of social dynamics.

Overall, this dream could be encouraging you to reflect on your social environment, the importance of supportive relationships, and your ability to navigate through obstacles. It may be beneficial to assess your current friendships and consider how they impact your sense of security and happiness.