Why Isn't President Bling-Bling Smiling?

From the BBC: Perhaps it's because he thinks Obama likes Angela Merkel better than him (I've often suspected that beneath the calm exterior of any head of state lurks the temperament of a preschooler). But I really think it's because this is probably the guy who's going to be taking charge of la Maison Blanche from his bestest chum, W.