Does sexual fantasies can make someone act against their will?

No: No unless they are psychotic.Eve the it is questionable.

Fantasies conflicts: Our mind represents our intellect and consciousness the combinations of thought and perception effects our emotion and imagination that also includes all unconscious processes. Desires not met can create conflicts. Its battle of id and ego can lead to depression anxiety and affects a lot in life.

Fantasy: This is sometimes an issue for obsessive compulsive disorder patients. A recurrent obsession does not an action make. It is not a premonition, does not predict that outcome, or define unconscious intent. If it is very distressing or you feel it predetermined and you feel you cannot stop, please urgently consult md, counselor, or temporary hospitalization if it includes violence. No shame, get well.