This isn’t a super old movie I don’t think… maybe a decade old is around when I saw it? But a fat woman (not a main character) becomes obsessed with the main male character. The male character is in a house (fancy house?) and uses a secret tunnel to crawl out of a room. She appears behind him while he’s crawling and quickly chases him. He exits the tunnel to a hallway in the house, but she gets stuck trying to get out. I really cannot remember anything about the male lead… but he was desperate to get away from the clingy fat woman.