Lovestruck: The Housemate (1993)

Juliette and Paul, married for three years move into their dream house, a beautiful villa away from the city, but they soon realize that the rent is too high for the two of them alone so they decide to rent out their spare room to a young woman named Nathalie who is none other than Paul's ex-mistress he abandoned and she is thirsty for revenge. She intends to make him regret not having kept his promises. Soon the old flames take a fire and they restart their affair. She wants him leave his wife, but he doesn't. So she tries to make him jealous by inviting a friend of hers named Stepen to stay over for the night.