I don't see the Saturn sq Mars aspect.I do see his Saturn conj your Pluto and squaring your Sun. Your Mars/Chiron also square his Pluto.
You were born at a time when he was in the process of eliminating a lot of things in his life, maybe outmoded ideas, so he had to be stringent about what he would keep on and what he would let go. There was a change that he felt very threatened by, something that he was in the process of losing. Along with that his confidence was shaken.
You remind him of things that are outside of his control, but things that he would still like to control just the same. You may remind him of what he lost. These things are nothing to do with you, per se. But he is triggering your natal Sun sq Pluto & Mercury sq Mars/Chiron with the synastric aspects I mentioned.
Don't let him be the start of a pattern of involvement with men who want to stay stuck in the negatives, or in what they can no longer have/achieve. These men will drain you and steal your life from you if you let them. Wasting time in unproductive arguments is wasting your life.
When transit Saturn conjoins your Pluto you'll know more about what I mean.
Lately it's been on your Chiron/Mars squaring your Merc which would've amounted to frustration with your response to the situation, past and present.
tSaturn's squaring his Pluto so he's probably getting some kind of message that he needs to tone it down. Cos, uh, Saturn by square doesn't take kindly to Pluto throwing the wrench into any kind of system. It only works when actions are for the good of all involved. That being both the integrity of the system, and those which the system serves. Or to be more clear, it's a crappy transit if you want to throw your weight around, because at this time it can't be about you, or in this case him.
Saturn is gonna Rx back here next yr, so that leads me to believe he's not going to get the full and complete message the first time.
G'luck.