"The Hidden Room: A Type of Love Story (#1.10)" (1991)
SUMMARY:
My memory of it isn't perfect, but the episode has stuck in my head for years. It was eerie (which was the intentional feel of the whole series) and heartbreaking, and not feeling attractive enough myself sometimes, it burned in my brain.
Basically, a "good looking" man meets a "plain" women in a bar and they connect. They start a relationship but he will never be seen with her in public.
Anything after that is a "spoiler".