If you dream of being in a treehouse, you are in a positive phase of self-development and becoming the person you are meant to be. You are concentrating on your own individuation.
To dream of building a treehouse represents your desire to get away from the problems of everyday life and find a sanctuary where you can feel peaceful. In this case, redecorating your room to make it more pleasant will be very benificial to you. This building dream can also foretell success in social situations.
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