What would you do if your boyfriend just disappears without saying anything?

We've been in a relationship for over a year and he seemed always so in love with me. Although he lives in spain and I live in London we keep in touch very often and send love tex messages he even wanted to marry me. But his last text he said he was having trouble and he was confused. Now it's been three weeks since he disappeared, when I called him he was cold and distant... But when a I go into the facebook I find that he's there, writing in his friends walls, making jokes and joining stupids groups! I don't know if should just stay silent or tell him what sad and upset he's making me