The Shape of Things
(2003)

Evelyn (Rachel Weisz) never actaully cared for Adam (Paul Rudd), he was only her final art thesis project.  Not only does she strain relationships between his friends (Gretchen Mol and Fred Weller) and he, but causes theirs to end as well.  Evelyn not only humilates Adam by revealing to the audience her true intentions but admonishes him for being so easily manipulated into doing whatever she wanted. 

The film ends without us knowing what the fallout of Eveyln's scheme was.

Thanks Blizzard!