Abhisara - The Tryst Questions and Answers

What were the changes in the time and condition when Vasavadatta and Upagupta met for the first time and again towards the end in Rabindranath Tagore’s poem “Abhisara – The Tryst”?

In Rabindranath Tagore’s poem “Abhisara — The Tryst” Vasavadatta, the beautiful young dancing girl invited Upagupta to her house, but he refused. Why do you think he did so?