Can counselling really save a marriage?

In short, it depends. It depends on whether you find the right counsellor. It depends on whether you are both determined and committed to each other. It depends on whether you are willing to be truthful, to be vulnerable, to work through painful emotions (perhaps going back further than the relationship), to stop using your usual self-defence tactics, to be open to new ideas, to try new approaches. To fail. To try again. To fail again. And try again. To be profoundly open to seeing the world in a way.

If you are both able to do this then yes counselling really can save a marriage.