Doctor Evan's Silence (1974)

In the surreal aftermath to a plane crash at sea Dr. Evan an eminent scientist is the only survivor to be taken into the confidence of the alien rescuers. He learns that the world with its weapons of mass destruction is not ready for the wonders of the culture of the pacifist visitors. The situation is further complicated by the close relationship that blossoms between the doctor and the female alien, and due to this relationship he is the only survivor allowed to retain his memory of the events, unlike the other survivors including his wife, whose memories are erased.