Ours was useful. We had nine sessions. He didnt admit his infidelities until after session 4, and then at home. I did feel that Relate steered fairly clear of that territory, although it was key for me, and even more so when not admitted.
However, it was also very clever, I thought. The (male) counsellor was clearly trying to support us to get to a place where h felt he could admit it. For example, he definitely managed to carefully challenge h on quite a number of his opinions, eg the sort of opinions which no doubt enabled h to feel justified about not admitting anything.
There was alot of 'she did this so I did that' stuff going on, and the counsellor was very helpful in pulling that apart.
I nearly fell over when h admitted so early and readily a fair heap of generally unreasonable behaviour, which he would have died before admitting at home.
The point there is that quite a ot of couples get into irresolvable arguments because of entrenched position, and at couples counselling, because there is a third and intelligent person in the room, it is much much harder to refuse to admit or accept the obvious.
So for me, it would have been helpful even if we had split up. Because couples counselling cant turn a total prick into someone who isnt, but it can shift someone who is selfish and defensive, if they are prepared to shift, and if they are bright enough to realise when they are seen through.
And if they dont shift with counselling, maybe they never would have, so that is useful to know.