The difference is that people who shoot others without a good reason would get punished even in the movie world. The creepy "romance" thing often ends up being rewarded in the movie world instead.

I think whether something is or isn't acceptable very much depends on the people involved. Though, I also find it unacceptable, just like you.

Most action heroes would spend years in prison had they done the same thing in real life. Movie "good reason" for shooting someone, beating someone or stealing a car would not cut it in real justice system at all.