"Abandonment" by one's spouse for more than one year is one of several grounds upon which a party may file for divorce in New York. Historically, this was a consideration for someone who opposed giving their spouse a basis to file for divorce. However in 2010, New York has joined every other state in also providing a "no-fault" basis for divorce, rendering "grounds for divorce" obsolete.
That said, leaving the marital residence, before or during a divorce action, does implicate several serious legal issues. First, if the spouse left behind in the home earns less than the one leaving, the court will likely issue an order for "interim maintenance" (spousal support) to the spouse left behind, to have sufficient funds to pay all of their ongoing living expenses at the residence. These interim spousal support awards follow standard formulas and can take away a large portion of the departing spouse's income; they are structured to require either one large monthly payment to the less-moneyed spouse, or a combination of direct payments of the marital home's bills plus separate monthly payments to the spouse, for general living expenses. Such an interim maintenance order will continue throughout the divorce proceeding until it is replaced by a final determination as to post-divorce maintenance (formerly known as "alimony").
In addition, assuming the children remain in the home, an interim child support order will be issued against the departing spouse according to a state formula, essentially based on that departing spouse's income. In contrast to maintenance, child support will be ordered even if that departing spouse earns less than the one in the home with the children.
If the parties do have children, a key consideration in deciding whether to leave the house is the issue of custody. While both spouses are in the home, the status quo is that both parents are home raising the children. If a spouse may be seeking primary physical custody, or even shared physical custody (i.e., relatively equal parenting time), it is critical to understand that leaving the home will establish a new status quo for a divorce trial, one in which the spouse staying in the home is the primary custodian. This new status quo tends to carry great weight in any ultimate custody decision.
On the other hand, if there is abusive conduct or fighting in the home, a spouse may face a choice, of either leaving or facing police responding to a domestic violence call. Under state laws, arrest is required if police are presented with credible allegations of domestic violence, which can include a spouse simply saying it occurred. Situations involving potential domestic violence allegations may require immediate court applications or hearings, for a court decision directing interim parenting time at separate residences, etc.
All or some of these issues may be relevant in any particular case in which a spouse leaves or is considering leaving the home. It is therefore strongly advised to seek the guidance of an experience matrimonial attorney.