Housesitter (1992)

She's turning his house into a home...hers!

After building his dream house, architect Newton Davis proposes marriage to his girlfriend, only to be summarily rejected. He seeks solace in a one-night stand with a waitress, never imagining that a woman he slept with once would end up posing as his wife. Gwen's ruse is so effective that by the time Newton learns of his "marriage," the entire town feels like they know him.