What is going on with him?

I love my man with all my heart but he seems to picking fights as of late. The most recent as follows, i have had some issues with a man that had been harring me as well as stalking, my boyfriend made me promise him to tell him if anything happens while he is not around and i told him i would. So something did happen, well nothing physical or negative and i happened to run into the man that hares me, but no words had been exchanged or anything. I did not tell my boyfriend about this because to me it was not an issue and i did not want to upset him for no reason. I happend to slip and say something the other day and he laid into me like i killed his best friend. I tried expaining to him why and that it was nothing, but he kept telling me that i made a promise and i did not uphold my end of the deal...this berating lasted for over an hour...I never wanted to withhold anything from him but it was nothing. Mind you he is a Recon Marine and deals with nasty people every day. Why was