The immaturity of a person, who is not willing to commit themselves to someone. They want to be with each other, but want to see other people, too.
Also an act of insecurity where the person needs more than one mate to satisfy themselves and to boost their ego.
Example for "Open Relationship." would be: I love you, but I like them, too, and I wanna see them. Can we be in an "Open Relationship."?