I don't understand

I truly don't understand why you chose to breakup instead of fight for us. He said I was the one, that he loved me the most out of anyone he's ever loved; my anxiety and need for constant reassurance made him lose all his patience for me and he ended it after a fight about the same issue - i wish fishing for him to say something (which was stupid bc i know he felt it) i was just in a anxious loop and needed him. I dont get why you give up especially when i had just started therapy. I begged, pleaded, cried, i did everything i could while in the relationship (he said he was 99% happy and he wasnt going anywhere almost daily). Why if all of that was good, throw us away for the 1 bad %...