What kind of group ceases to exist if even one member leaves the group?

dyads

Explanation:

A dyad is a kind of group that ceases to exist if even one member of leaves the group.

Such groups consists usually of two people.

A dyad is used in sociology to refer to a group of two people It can be a brother and a sister Such groups can be terminated when one member of the group pulls out or dies. Dyads are the simplest group structures known. Members of a dyad can be linked by education, romance, business, e. t. c