"Mom just doesn't understand!"
It's a common complaint I hear from boys - but what is their definition of "being understood?"
Let's start with your own emotions - how would you feel if someone had power over what you could and could not do - and didn't understand what was happening in your life? You'd feel frustrated, depressed, angry; have you seen any of those characteristic in your son?
Understanding that a person IS going through difficult times does not mean we have to understand WHAT those difficulties are. In other words; just knowing someone has compassion concerning what we are experiencing is tough and acknowledging it - shows compassion for what we are going through. I can tell someone with a broken leg, "man, that really stinks to not be able to walk for a week." Shows compassion - even if I've never had a broken leg.
I find boys really respond to a simple statement that; "it's really tough to deal with teachers or school or girl friends"; but NOT saying, "I understand" which is implying I have gone through what they are going through; None of us have ever gone through the exact circumstances another person is experiencing and especially a mother talking to a teenage son. But saying it must be tough and even though you've never experienced it; you know it must be rough is something they will hear. If you try this approach you will see a look of appreciation in their eyes.
Remember the BAM program - THEY HEARD YOU - your son will probably not respond "oh, thank you mom". But they did hear you and do appreciate the fact you are trying to "understand" the toughness of this period of time in their lives.