It doesnt last long though. Ali Larter (Jay and Silent Bob Strike Back, Legally Blonde) is psycho and in schizo mode. Her attempts are never recipricated so she eventually carries this 'you dont have to like me, just eff me' vibe to tempt Derek (Idris Elba).
Ali Larter has such a strong personality so she plays this type of character very well.
Sharon (Beyonce Knowles), at first, is a funny jealous woman who takes the 'Temp' situation in stride. During the fight scene she seemed so poised and sophisticated even. I dont know if that was good acting or amateurism.
Crazy woman movies have a formula. Intense flirting, making plays for sympathy with suicide attempts and fighting to the death. But you know how these things end, All's fair when love is war.