What happens when one person just walks about the door, but the separation is voluntary?
Just leaving by mutual agreement is not a divorce. An agreement to separate may be a preliminary for a no-fault divorce, but just leaving is not.
For example, when the husband and wife separate on a trial basis, both may agree to it, but a trial separation -- one sometimes undertaken to take stock of the marriage -- is not grounds for a divorce in itself.
Desertion must be certain criteria, and most but not all states consider it ground for divorce.
Desertion, like adultery, is a difficult route to divorce, and like adultery it not used much. In general, most states require the plaintiff, the party who is abandoned, prove that the defendant left the home for more than one year, did so without the agreement of the spouse, failed to pay support and that the reason for the departure was not caused by the plaintiff. Abandonment or desertion means that the either the husband or the wife refuse the duties and obligations associated with the marriage.
Some states have laws saying that if one spouse has moved out, it demonstrates an irretrievable breakdown of the marriage, sufficient for a divorce.
Abandonment is not the same as a woman fleeing domestic violence in a crisis, nor it is the same as a man announcing his intentions to divorce his wife and then moving out.
Like many facets of marital and family law, abandonment has two sides. As a strategy for coping with the domestic turmoil of a failed marriage, just leaving may have legal repercussions that weaken one’s case after he or she thinks better of it and decides to formally end the marriage. This is particularly true when there are children because it may be much more difficult for the leaver to make a strong case that he or she is fit parent if he or she walked away for a significant period of time.