I'm sure you speak for the preponderance of women, i.e., she's very likely right and he's very likely wrong.Perhaps she had perfectly valid reasons for leaving him. Maybe he cheated. Who knows, certainly not you. Maybe the problem was with his choice of woman and maybe the problem was with his treatment of said woman. I do know some people who have/had successful 3rd marriages after messing up the first 2, but OP would need to figure out what he's doing wrong before taking that step.
That's WHY he should avoid wife#3 like the plague.