What does it mean for a boy to send himself eternal flowers?

There is a story about the eternal flower in southern Europe.

It is said that a couple who loved each other deeply in the war are about to leave. Before going to war, the boy left a bunch of roses and a letter to the girl. The boy told the girl that when the last petal of the bouquet of roses fell, it was time for her to forget him and start a new life. So the girl prayed for the boy to come back safely every day. But until the smell of roses faded, the boy was never heard from again. But magically, none of the flowers in the vase fell. Finally, one day, the tired boy came back to the girl's door wearing a victory shirt with a deposited scar. From then on, I will join hands all my life and never part. But the withered rose still stands. As a result, the story of the couple being cared for by the god of luck has been passed down. So far, as long as boys and girls fall in love in Europe, they will leave a bunch of roses. Or put the petals in the Bible, or make them into eternal flowers that never fade. Pray to be as happy and lucky as them forever.

Therefore, the flower language of the eternal flower is "love eternity"