This movie is Asian, probably Japanese. It is at least ten years old.
The story is as follows: a female assassin falls in love with a guy, but her boss wants the guy dead. He has situs inversus (i.e. his heart is on the right side of his torso). At one point she has to shoot him, so shoots him on the left side (the usual side for the heart). He survives.
I find the film similar to Point of No Return.
Note: Both answers currently provided have been checked and are not the film in question.