a group separating from a larger one

withdrawal

the act of detaching or being detached; the state of not being influenced by personal opinions

disconnection

the artificial process of removing waste products from the blood, e.g. when the kidneys are not working

being apart; break-up

a division into two (usually opposite) groups or mutually exclusive pairs

division

the act of disagreement; the absence of agreement

dispute, quarrel

the breaking up or ending (of a marriage, partnership, formal meeting etc)

separation, rupture

the absence of unity

division

the process of dividing or being divided

separation, disconnection

(an instance of) the legal ending of a marriage so that the man and woman are free to marry again

split-up of marriage

the division (e.g. of a country) into parts ; something that separates or divides, e.g. a thin wall between rooms

divider, division

(an instance of) a division of an organization (especially Church) into two or more groups

separation

(an act of) separating or being separated or separate; an instance, period, of not being together

being apart; break-up

severance pay' = money paid to an employee, e.g. when a contract has ended

division