【Separate】 ,  【part】 ,  【divide】 ,  【sever】 ,  【sunder】 ,  【divorce】  can all mean to become or cause to become disunited or disjoined.

【Separate】 implies a putting or keeping apart; it may suggest a scattering or dispersion of units or a removal of one from the other or the presence of an intervening thing or things.

【Part】 usually suggests the separation of two persons or things in close union or association; often also it suggests a complete or final separation (as by death or violence).

【Divide】 commonly stresses the idea of parts, groups, or sections resulting from literal or figurative cutting, breaking, or branching.

【Divide】 often, in addition, carries an implication of apportioning, distributing, or sharing.

Often  【divide】  is used in place of  【separate】 , especially when mutual antagonism or wide separation is connoted.

【Sever】 adds the implication of violence by or as if by cutting and frequently applies to the separation of a 【part】 from the whole or of persons or things that are joined in affection, close affinity, or natural association.

【Sunder】 often implies a violent rending or wrenching apart.

【Divorce】 implies the separation of two or more things so closely associated that they interact upon each other or work well only in union with each other.

【Divorce】  can specifically refer to the legal dissolution of a marriage, a use in which it contrasts with  【separate】  which implies a mutually agreed ending of cohabitation without actual legal termination of the marital state.