Dreaming of someone buying a house can symbolize several things, depending on the context and emotions within the dream. Generally, houses in dreams represent the self or one's personal life and experiences. Here are a few interpretations:

1. Change and New Beginnings: A house purchase often signifies a new chapter in life. It may represent growth and new opportunities for you or the person in your dream.
2. Stability and Security: Buying a house can reflect desires for stability and a secure foundation. This might indicate a longing for comfort and security in your own life.
3. Relationship Dynamics: If the person buying the house is someone close to you, it could symbolize your feelings about their life changes or decisions. It may also reflect changes in your relationship with that person.
4. Personal Growth or Aspirations: This dream could represent your own aspirations, ambitions, or desires for independence. It might encourage you to consider your goals and where you want to establish your own roots.

Reflecting on your feelings during the dream and any personal circumstances can provide further insight into its meaning for you.