A Young Zelkova(1968)

Suk-hee's mother is remarried to a man who has a son a year senior than Suk-hee. The two don't get along well first, but soon they grow intimate. Suk-hee learns, though, that she needs to give up her love for her mother's happiness. One day she leaves her mother and her new family, and goes on her way to her hometown, where she sees a Zelkova tree.