Boyfriend is mad that I posed nude for a friend's college work?

He's barely even my boyfriend but let's call him that due to a lack of a better word.

My friend is a fine arts major. It was purely artistic and not very explicit anyway. She used 3 shots for her project: one of my belly, one of my collarbones/neck and one where I'm sitting butt naked on the floor. The 3rd one is the most graphic but really all you can see is my back and like my buttcrack lol.

This "boyfriend" got really pissed that I let someone photograph me like that even though this happened 2 years before I even knew he existed.

Is he being irrational or is that really a valid reason to be mad at someone? I feel like at this point he's just trying to pick a fight honestly.
Boyfriend is mad that I posed nude for a friend's college work?
Post Opinion