I’m sorry I can’t remember if this is from a show or movie, but I think it’s from a movie.
It’s a romance where the man is a very serious, somber character, never laughs or smiles. There is a photographer friend who takes photos of the female love interest, and one day the man comes over and sees the photos laid out on a table. As he looks at a photo of her, he smiles, not realizing that the photographer sees him, and takes a picture of him.
Later, the female LI is visiting the photographer, and notices the photo of the male LI smiling. She asks the photographer how they got him to smile, and the photographer is coy about it and says they don’t know.
This has been bothering me for a while now, hope someone can help!