I'm also 35 and feel exactly the same way. This often gets me in trouble with my wife when she exclaims "how could x have done y!" and I proceed to stick my foot in mouth by saying "maybe they were thinking z".
Coincidentally, I am 35 and feel the same way :) Most of us are just working hard to get through the day and we're all going to screw up sometimes. I always try to offer understanding for others' mistakes, and hopefully I'll receive the same.
Don't give an objective analysis of the situation with an account of the other person's point of view, especially if your wife or girlfriend is in the midst of emotionally venting. It won't be appreciated.
Once she's cooled off and feels listened to and heard, then you can start to reintroduce logical analysis and 'what was the other party thinking and why did they do what they did'. But not right away.