Bo Peep, who for the majority of the film eschewed the need for a toy to have a kid and espoused the merits of a free life on the road, realizes that she would like to be with a kid again, that she wants to go back to being a toy in a bedroom with this little girl. She didn't think she wanted that life anymore, but her connection with this child changes things for Bo Peep. In this moment, Woody would have understood that he once again has to let Bo go.