All those people spittin their critiques are too involved into what a social net is supposed to be, but they don't know anything about art nor tattoos.
"What will happen after Facebook fades away or the users change their profile photos? What will happen if she wants to 'unfollow'?" Nothing at all!
Come on, the art on her arm is not about Facebook or updated avatars, it's about something special and beautiful for her, and it's a work of art by itself, no matter Facebook or those people inked on the tattoo sleve go away or stay. It's not pathetic at all. It's art, it's her arm, it's her will and she likes it, period. If you are not intelligent enough to understand the difference, then I guess the wrong ones are you.