I was the same way. I tried to be the mediator. However, it did wear me down some. But I thought it was my job in a sense as part of the triad.
However, after listening to other people in triads, I think a better approach is not to be the mediator. Let them handle it and try to stay out of it. I think you can be a sympathetic ear, but don't take sides.
I tried way too often in relationships to take on the role of a counselor. I think it hurt the relationship more than it helped it. Or maybe the relationship was doomed from the start. I don't know.