Not really a romantic movie but I remember when I watched the series Dexter, in the first sesons, probably season 4.
At a moment, he starts to have a stable relationship with a woman. The character we followed who was a psychopath was starting to have some feelings for someone. We could really see he was truly in love with her. And when she is killed I cried a lot :')

After that romantic period of an absolutely not romantic series I was really chocked and that was hard to continue the series. The bad side is that it was probably the best season and after that everything was getting worst and worst !PIZZA