Complex sentence: As a ploy to separate the lovers, their parents impose a condition that Vasu and Sapna should stay away from each other for a year, and after such a period if they still want to get together they can get married.
Split into simpler sentences: As a ploy to separate the lovers, their parents impose a condition that Vasu and Sapna should stay away from each other for a year. After such a period, if they still want to get together, they can get married.