Deciding to separate does not end the relationship if you have children together. It changes it into one you will be managing for years, and that version is worth doing deliberately.
Divorce is treated as an event. It is closer to a long process with a legal moment somewhere in the middle, and the hardest parts often arrive well after the paperwork is finished.
During
Counselling here is usually about keeping decisions out of the argument: how to tell the children, how to divide what you owned, how to speak to each other when everything either of you says is being kept score of. Some practitioners see separating couples together; others see each person alone.
Afterwards
Grief after a separation is real grief, and it does not respect who left. So is the loneliness of a house that is suddenly quiet half the week, and the strange guilt of feeling relieved.
Co-parenting
If you have children you are not finished with each other. Practitioners who work with separated parents focus on the handovers, the messages, and the discipline of not making the child the messenger.
Counselling is not mediation and does not settle finances or contact arrangements. A mediator or solicitor does that.