9. Eric Woodruff and Darren Ritter
This one should have worked! Eric Woodruff (Curtis Edward Jackson) and Darren Ritter (Daniel Kyri) were a charming pair in Chicago Fire seasons 7-8, but their constant breaking up and getting back together felt a bit too manufactured to fully enjoy.
This was especially the case in season 10, when Woodruff decided to call it quits because he couldn't relate to Ritter's firefighter lifestyle. It was an anticlimactic way to wrap up a multi-season romance, and it retroactively soured the whole thing.