Main Couple doesn't end up together (anime)
AnimeSpoiler
Not all of these anime have the romance tag, but at some point the main characters have shown romantic interest in each other and for whatever reason they didn't end up together.
This list is a cautionary tale of sorts.
manga version: myanimelist DOT net/stacks/25165
This list is a cautionary tale of sorts.
manga version: myanimelist DOT net/stacks/25165