*SPOILER ALERT*
It's a decent time waster, though inspiring, it's not all that realistic when it came to certain things but mainly the ending.
The cops would not just stop the investigation after Ginny calls the cops, especially with that guy's parents and that type of money. Eventually, with hired PI's they would have known her cell phone was pinging on the tower near his house, well before he had even left for work. On top of that those letters? Like he wouldn't save any letters he wrote? He didn't know where she even was for them to communicate back and forth on the phone let alone sending a few letters.
Lastly, they will be doing an autopsy eventually and the damage done to him besides being kicked off the ledge would show up, especially them bootprints.
Then she calls her friend, telling her she can't do it, obviously proving premeditated murder or at least manslaughter.
You really have to suspend your disbelief at some points