Tonton Streaming The Twilight Zone (2002) S1E25 - Fair Warning

Tina, a flower shop clerk, finds herself threatened by a seemingly-deranged man named George who mysteriously disappears after asking him to stop from killing her. When she finds him he has a perfect alibi and claims he doesn't know her. George keeps visiting her and no one ever sees him except Tina. Tina begins to question her sanity.