So I Married an Axe Murderer (1993)

Just after a bad breakup, Charlie MacKenzie (Mike Myers) falls for lovely butcher Harriet Michaels (Nancy Travis) and introduces her to his parents. Unfortunately Charlie's fear of commitment leads him down a paranoid spiral as he begins to suspect that Harriet is actually a notorious serial killer -- "Mrs. X" -- wanted in connection with a string of bizarre honeymoon killings. Despite his initial fear, Charlie proposes to Harriet. But while on his honeymoon with her, he begins to fear his initial suspicion may be correct.