Dreams about being in a reality show like Big Brother often reflect feelings of exposure, competition, or the desire for connection. In your dream, the connection with the girlfriend might symbolize a longing for intimacy or understanding in your waking life, especially following a significant change or loss.

Her pretending not to know you after leaving the house could indicate feelings of uncertainty or fear about how relationships change in different environments. It may also suggest concerns about how others perceive you or your connections when removed from a particular context.

The mention of her appearing scared could represent your own feelings of vulnerability or anxiety regarding relationships, especially in the wake of changes or potential rejections.

Finally, the encounter with an old friend signifies a desire to reconnect with the past or revisit old memories. This could suggest that you are reflecting on your past relationships and how they shape your current emotional landscape.

Overall, this dream points to themes of connection, fear of change, and reflection on past relationships. Consider how these themes might relate to your current life situation and what emotions they evoke for you.