Wall-E returned to the spot he last saw the dog. The joyful Boston terrier wasn't there and gave no signs as to where it went. After watching the video of Lena, Wall-E decided to name it Lena. So Wall-E just started calling in his robot voice, "Leeeeee-na." Wall-E started wandering off into the abyss. It was beyond the civilization and into unexplored territory.
Eve came along and joined Wall-E. Eve could not let Wall-E go out there alone. She knew Wall-E's curiosity could get him into a lot of trouble especially in unknown lands. Plus if this creature just appeared, perhaps others did too. She saw a video of a bear in their video library. She knew that there could be those types of creatures if that Boston terrier was around.
Wall-E had gone out of sight of the civilization searching aimlessly for the dog. And Eve was not quite ready to let him go further. Eve raced to Wall-E's side and robotically cried "Walllll-E." She tried to push Wall-E the other way but Wall-E was in a trance. Searching for the dog that fulfilled his joys just a day earlier. "Wall-EEEEE" Eve cried again hoping to get Wall-E to turn around she swung around and started pulling him. She had begun to lose faith that she could dissuade Wall-E.
Against Eve's better judgment and coinciding with Wall-E's unparalleled curiosity, the two robots slid away from humanity and into the wild.