There is a difference between physical separation (moving out) and legal separation (getting a court order that you are separated).
You may file a petition in court for legal separation if you are planning to be separated for a long time and want the court to address support, property or debts during the separation. You can also address custody and visitation if you have children. However, this process is almost the same as filing for divorce and may take a long time. At the end, you will still be married. If you want to divorce in the future, you will need to file a new action. This can be costly because you will pay for two different court proceedings.
Benefits of legal separation v. regular divorce
There may be times when legal separation is appropriate. Some people, for personal reasons, do not want to be “divorced.” Some employers allow legally separated partners to stay on their health insurance, but the partner would be dropped if they got a divorce. Additionally, if one partner is building up significant debt or wasting funds (by gambling, for example), legally separating and dividing assets and debts can protect the non-spending partner.
Divorce after legal separation
If you decide you do want a divorce after the legal separation is granted, you have to file for divorce with the court. Assets and debts that were already divided will not be re-addressed, but if you have jointly acquired additional property or debts since the separation was granted, that will have to be divided.
In short, most people decide that divorce is the best way to handle their situation, but legal separation can be appropriate in some cases. Just be careful not to indicate that you are legally separated when you are only physically separated.