The impact of separating and moving out can be very traumatic under any circumstances. It is even more traumatic if one party is taking all the actions “solo” while the other party is feeling abandoned and rejected.
The party that is being left may be so affected by the situation that it puts him/her psychologically in a very bad place. Anger and the need for revenge, amplified by the feeling of abandonment, may make one spouse less amenable to working with the other spouse on an equitable agreement.
In this excellent article Jennifer Safian offers a few thoughts on what you may want to do if you move out before you have worked out the terms of your divorce, in order to try to maintain an amicable process with your spouse.