Today we were arguing about induction of suicide, the theme was the following: if you pretend to commit suicide and your girlfriend\boyfriend didn't know it was fake and consequently commits suicide themselves, are you liable for any legal penalties?
Generally speaking, taking an action which causes someone to commit suicide does not give rise to civil or criminal liability unless it was intended to cause someone's death.
For example, in Colorado, "a person commits manslaughter if: . . . (b) such person intentionally causes or aids another person to commit suicide." Colo. Rev. Stat. § 18-3-104(1) (in the pertinent part). The same statute has an exception for palliative care and for assisted suicide in circumstances where it is authorized by a citizen enacted statute. Ordinarily, manslaughter would involve merely recklessly causing the death of another.
There is generally no criminal liability for recklessly or negligently causing a suicide, nor is there civil liability for doing so, although in a civil lawsuit, one can be sued for "intentional infliction of emotional distress" that is so extreme as to go beyond the bounds of human decency even if the tortfeasor does not personally inflict any physical harm upon the distressed person.
There can be civil liability for emotional distress that a person suffers as a result of a tortfeasor's negligence as well, but that is generally possible only in circumstances where the emotional distress is a side effect of a personal physical injury.
So, Juliet would probably not face either criminal or civil liability for the death of Romeo caused by his discovery of her fake suicide, not that it matters, because she punishes herself far more severely anyway.