We have - my wife had an affair over a long time. I also had one for a short time afterwards, as I was all over the place.
Both of us ended them before the other found out.
Now they are both in the open, we have fully committed to making our marriage work (for us as a couple, as well as for the sake of our DCs).
It's taken a lot of time and work on both our parts - to accept responsibility for what we've both done to each other, and things aren't like they used to be.
However, I'm not sure we were always totally honest with each other beforehand (we got together very young, had a "perfect" relationship and family that came with a lot of pressure/expectation from both our extended families).
Where we are now is much healthier.
I'm sure there will still be related issues in our future, but as long as we continue to be open and honest with each other about things, I'm fairly confident we will have a good marriage.
We tried counselling, but it didn't work for us - we've got to a point where we can talk about it all openly, which works better for us.
We find that text conversations often are a good medium for this, as it allows us to consider our responses, and remove some of the emotion from the discussion.
BUT - it has only worked because we have fully owned our own mistakes, and have been understanding and patient with each other in terms of regaining trust (though i think this will be an ongoing thing).
We both agree that what we have is valuable to both of us, and that it's worth the effort.
It wouldn't work if it was only one of us driving it all.