Soo annoyed!

So I am wondering why in the world by bf is so insecure....I mean I know he hasn't cheated on me or wouldn't he loves me so much.  He just got mad at me because his cousin tweeted me and I tweeted him back...about nothing inappropriate just about my shopping habits...I mean come on now really....relax it is not a big deal...I do not know why he i so insecure and always ask this all the time...it is so stupid...it makes me very mad...I have done nothing wrong for him to think anything like this of me...idk what to do anymore...i am wondering if other woman out there know what I am talking about....