What does every short message that can turn Lin Beixing back in time mean?

Every short message that can make Lin Beixing go back to the past is a moment of regret for Zhang Wansen.

From the TV series, the twinkling stars mean that the heroine Lin Beixing can return to the college entrance examination by deleting the short messages in her mobile phone, but every short message that can make Lin Beixing return to the past is a moment of regret for Zhang Wansen.

With love in the world, there will be regrets, and with regrets, yearning will become heavier. "