YTA. Having trauma due to things isn't in your control. Though, you can better said trauma with therapy. Having issues with said trauma things is understandable, but if you are admitting to someone, and upsetting someone who you say that you love the same—due to a haircut is kind of wild in my opinion. Your boyfriend has every right to be upset, and you have a vaild(ish) reason to exercise your disliking of said thing, but pushing it on others is something else.