term:

Desertion

desertion n

: the forsaking of a person, post, or relationship: as
a : permanent withdrawal from living with one's spouse without the spouse's consent and without cause or justification NOTE: Desertion is a ground for divorce in many states.
b : intentional permanent termination of custody over one's child
;also
: abandonment
c : abandonment of military duty without leave and without the intent to return

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.