Big but: The lead character, Calvin, is not believable as a "genius novelist" nor even as a pretty good one. Why? He has no idea how to make Ruby, whom he completely controls, subtle and complex the way any good novelist would his characters.
He paints her happy and sad, joyful and childishly clinging with such broad brush strokes he is an incompetent "inventor" of a character/person, let alone his dream girl. If you or I created an automaton, WE might swing back and forth to the extremes while trying to adjust his/her behavior. Calvin should be an expert not a tyro at subtle shades of behavior. Granted, if he got her just right, we would have no crisis to force the story to a resolution.
And the resolution is Hollywood sugar. In Europe or Israel, the hero would be left with the sad results of his failure. (He stares out to sea on a deserted beach to ponder what happened and his bleak future?) Here, the filmmakers insist we leave the theater feeling good about Calvin and Ruby.