Couples who separate permanently are still legally married. However long they are separated, they remain married until they are legally and finally divorced.
Sometimes a counseling, and sound the beam and bulkhead of the ship of marriage to see if the vessel is sound enough to saved.
Even when couples agree to divorce, very often one or both spouses need time to adjust to the new situation. A permanent separation fills this gap. Sometimes couples who separate permanently do nothing more for some time.
As divorce lawyers will attest, in most marriages where a couple have made a separation is the catchup time.
Very often the beginning of a permanent assets for distribution.
Some jurisdictions permit divorcing couples to life together even when divorcing; others require a physical separation -- separate residences. In a permanent separation, most couples who can live apart physically do so.
A permanent jurisdiction to another.
The act of separating, which is accompanied by announcements to family and friends that a divorce is in the offing, places a couple in a penumbra: the de jure. All manner of issues and problems can arise during this period, which, depending on the actions decisions of the spouses, lasts weeks, months and even years in some cases.
These issues and problems include, but are not limited to, mortgage.
In this, the phrase "during the marriage" comes into play because courts need a concept of the filing.
See also "During the Marriage."