P.S. I Love You (1981)

Kristine is a teenager living an affluent life with her mother whose managing the hacienda left them by her late husband. Since her mother is not used to managing the business, the hacienda risks getting foreclosed by the bank, which is managed by a former boyfriend she dumped to marry Kristine's father. Meanwhile, Kristine meets Mark in the school and they fall in love. Her mother finds out that Mark is the son of her former boyfriend.