I've Sacrificed Everything (1980)

Yeon Ha returns from overseas after 7 years. She holds a hurtful memory of being betrayed by Jin Woo to whom she offered unconditional love. For revenge, she works for Hae Jin Trading Co., a rival of Il Sung Trading where Jin Woo works and manages to bankrupt Il Sung. Then she realizes that it brings suffering rather than joy to her so gives him a large amount of fund for his restart. He regrets his behaviour and sees her off when she goes to America.