1. Clearly express gratitude and respect: I would like to thank you for having such a favorable impression of me or proposing to establish a relationship, which makes me feel honored. I have always appreciated some of your traits, but I believe that at this stage, maintaining our existing friendly relationship would be more comfortable and natural.
2. Elaborate on personal feelings and decisions: After careful consideration, I have realized that I am currently not ready to enter deeper relationships. This is entirely my personal decision and has nothing to do with your value or charm. I hope you can understand and respect my choice.
3. Propose expectations for future friendly coexistence: Although I cannot accept your proposal, I cherish our friendship very much and hope that we can continue to get along friendly like we do now. If there is anything I need help with in the future, or just want to chat, I am willing to listen and support you.