Mila Kunis walks the fine line between friendship and romance

There are some lines you just never cross.In the new movie “Friends with Benefits,” Mila Kunis (“Black Swan”) and Justin Timberlake (“The Social Network”) try to negotiate the complicated avenues when two friends become involved. Kunis plays Jamie, a headhunter in a leading job agency that befriends one of her assets, Timberlake’s character, Dylan—a hotshot young art director for an LA-based