Writing to his brother Modest, Pyotr was pleased with him as a librettist and how the Queen of Spades death scene was arranged. While he demanded fewer scenes, he worried that Act III may end up dull without women actors. The fate of Lisa's character was written into Act III.
In June of 1878, Pyotr wrote to his brother Modest that he played through entire Eugene Onegin, and confided that the total audience of one was moved to tears and paid a thousand compliments to the composer. He hoped future audiences would feel the same way as the composer.
Apparently, Modest Tchaikovsky, composer's brother, criticized Onegin for potentially lack of scenic effect and action. This annoyed Pyotr, but he didn't care. He was immersed in the opera, in love with Tatyana's image, and enchanted by Pushkin's verse.