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I also remember one scene where the guy was talking to a girl, then he turned away and started crying, and said "I can't fall in love again... but you... you.... YOU...." or something. He did this again later to several girls.
Oh, I forgot to mention the redhead was an absolute Tsundere.
Would that be "Heartbreaker" starring Vanessa Paradis and Romain Duris?
Edited by HighFunctioningSociopath
That looks like it! Thank you!
A French film where this guy presumably breaks up couples for a living, then he meets this girl with long, red hair, who has a slutty best friend. I recall the slutty friend seeing the guy and saying "my pussy is itching for a shag" - or at least, that's what the subtitles said. Any ideas?