This dream presents a complex mix of emotions and situations that may reflect your subconscious thoughts and feelings. Here are some possible interpretations of the key elements:

1. Supermarket and Protest: The supermarket could symbolize a place of choices and abundance, while the protest may represent feelings of frustration or a desire for change in your life or environment. The idea of people "crashing out" suggests that you might be grappling with issues related to loss or the impact of others' struggles on your own life.
2. Old Gym Teacher: The presence of your old gym teacher could symbolize authority or a figure from your past that represents discipline or physicality. Their involvement in the discussion of job loss may reflect your concerns about stability and support in your life.
3. Transforming Relationships: The transition from your sister to your friend suggests a change in your support system or feelings about those close to you. This could represent a blending of emotions, where you’re relying on familiar faces in challenging situations.
4. Harassment and Panic: The feeling of being harassed by a figure from your past might indicate unresolved trauma or anxiety about being vulnerable. Your pleas for the situation to stop reveal a need for boundaries and a desire for safety.
5. Transformation of Characters: The shift from the middle school guy to your boyfriend signifies a transformation in how you perceive relationships. This could point to fears about trust, vulnerability, and how past experiences influence current dynamics.
6. Desolate Woods and Lake: The woods symbolize the unknown or fear of abandonment, while the lake might represent emotional depths or potential danger. Your panic about being left there reflects anxiety about losing control or being in a vulnerable position.
7. Tossing and Falling: The act of being tossed and then falling can symbolize feelings of instability in your relationship or in your life. It may express a fear of being let down or the unpredictability of those you care about.

Overall, this dream could be highlighting your feelings of vulnerability, fear of loss, and the complexities of your relationships. It might be helpful for you to explore these emotions further in your waking life. Consider reflecting on your support systems and how you can establish boundaries to feel safer in your relationships. If the themes resonate deeply, talking to someone you trust or a professional could provide additional support.