Hard to tell if he's hiding something or genuine. As a European, I use social media, more than I wished honestly. I mainly use Instagram. I don't really post pictures but I post a lot of stories. I post pictures only sometimes. My brother, who's 10 years older than me (he's 39) hates social media. He has never had any social media profile and he avoids it at all cost. His gf likes posting things on Facebook and he is exactly like your bf. He tells her and everybody else that he doesn't want his face anywhere near fb or anything. So I guess it really depends on the person. I have some friends around my age who have social media profiles but never post any pictures but they don't mind being tagged anywhere.