Tonton Streaming Tales from the Darkside (1984) S1E6 - Slippage

A young ad-design artist begins to literally "slip" out of reality. Slowly but surely he seems to be fading out of existence: first his payroll checks disappear, then his high school not only fails to mail him about their reunion, but has no records of his existence. The artist soon realizes that since he's drifted through life, he's basically "slipping through the cracks". Even his mother has no memory of him. At the end, even his wife and best friend (now the woman's husband in this new reality) forget he ever existed.