Okay, for the AU content lovers, I have a theory.
This place is beautiful. Just Google search it. Tell me that it's not a perfect place for proposal?
Plus I believe they started in haveli (May 20ish), and he took her to this Palace like place for the next big step, and the wedding will be at a palace as well.
If it doesn't happen, consider this as my AU ff and don't kill me. Alice has been wearing that promise ring since he gave it to her.