Will Rather Become a Ball of Fire (1986)

Ae-shim, a waitress, meets Yun-gu and ends up living with him at a rest area restaurant by the industrial highway. However, Yun-gu treats Ae-shim badly. One day, the vagabond Jun-tae shows up in front of Ae-shim. He seduces her and they plan to kill Yun-gu and get his fortune. But Yun-gu catches on to Ae-shim's betrayal and plotting. He still loves her though. Yun-gu decides that the only way he and Ae-shim can be together forever is to die together. Yun-gu pretends to be a pawn in Ae-shim's plans but then leaps off the cliff with her, killing them both. Jun-tae ends up getting caught by the police.