You could say something like.."Its hard looking back with regret".. or "sometimes I feel the same way"...something noncomittal and validating of his feeling. When in doubt you can try to rephrase what he says just with different words or by summarizing. It doesn't mean you agree or disagree, just that you are hearing him.
M44 H46 T21 Married 16y D14 D12 Bomb 12/08(EA), (PA/Separation)1/09 to 5/09 Home/MC 5/09 to 12/09 Leaves 12/09 Files for Divorce Divorce final 6/30/10.