Choi have to leave. He asked for time, for him to weigh things out. On who should he choose. The present or the past ... on to whom should he give his one true love.
Bubbles though in pain ... is very much willing to wait. She needs a sign. A sign to know if she will count on Choi's words that he loves her and she is his happiness or if she will have to move on with her life without Choi.
For Bubbles, life must go on. Because it is a gift from above. So when they are about to part ways, she gave him her most precious gem. A flower ring. A ring that must be returned because it is part of a very important collection in her life. Choi understand that Bubbles is very sentimental. The sign, Choi must return the ring, no matter what his decision. If he returns the ring personnaly, it means, he had choose Bubbles to be his love of his life. But if he returns the ring in other manner, it means, he had choose the past to be his beloved.
Bubbles knew from the start that no matter what, even without the sign, she will wait, with all her heart, with all her being, with all her soul, with all her mind and all of her. And all she wanted is his happiness.