Living Together Separately
The date a couple separates can be important in a divorce, especially in community property states. But a hit-the-road-Jack departure is not required for a couple to be separated. In California, for example, the date of separation is determined by intent; it is the date when one spouse decides not to continue the marriage. A divorcing couple can live separately in one house.
Personal Service of Process
You cannot obtain a divorce without officially notifying your spouse about the divorce action by following your state's service of process rules. Generally, serving process requires that you enlist another adult to hand your spouse a copy of the court-stamped divorce papers. The person can hand your spouse the papers at his residence, office, or anywhere in between.
Personal service is sometimes difficult. After a process server has made repeated attempts to serve someone personally, many states allow her to leave the papers at his office with someone in charge, or at his dwelling with another adult who lives there. When you are the other adult sharing a premises with your spouse, the latter option (substitute service at home) is not an acceptable one, given your status as opposing party in the divorce action.