Yebbuen Namja (예쁜남자, roughly translated as "Pretty/Beautiful Man/Boy"; also titled Bel Ami in some circles) is a 17-volume manhwa series created by Chon Kye-Young and later adapted into a live-action drama miniseries broadcast on KBN.
When the improbably handsome social climber Dokgo Ma-Te is given an opportunity to make himself rich and successful by using his good looks to seduce a number of powerful women, he takes it. But his devoted, lovestruck new assistant, Kim Bo-Tong — a ditzy, homely girl from a poor family — begins to attract his eye, and he worries he might be falling for her in turn.
Volume 7, Chapter 3
Kim and her friend David go to a local buffet and take advantage of the generous portions, shocking Dokgo; hours after, the now hugely stuffed Kim decides to ride the subway home, where — much to her embarrassment — a commuter offers her his seat, thinking she's pregnant.