I actually don't think the Jake-actor is that bad. The character is obviously very restrained and secret, so there's nothing much to emote for him. But he's doing what he can with the script.

The Cassie-actress on the other hand. There was this one scene where Jake "broke up" with he and she was supposed to be hurt and confused. So the actress did what every half-assed actress would do: Look left, then right, then left again, sigh and leave stage. If it wouldn't be so sad...

I have no idea how the same people who cast Nina Dobrev also cast this girl.