Why would a guy change his status to 'in a relationship' a week after he said he hadn't met anyone new?

Alot of guys do this. They will not announce they are going out with someone, but will change something somewhere that will cause someone to realise that he's found someone.

It sometimes happens when a guy goes out with someone too soon after he breaks up with his ex. He will not say a word, but he will change a status on facebook, myspace, bebo, or whatever one he uses most.

The reason could be because the girl he's seeing does not like the fact his status says Single. Therefore he has to change it and risk his friendships otherwise risk his relationship.

People dick around on facebook (You are talking about facebook right?) all the time. Well, I suppose it could be a show for his family. I personally know the pain it is to get prodded about having a significant other... or not. But he's probably in your age range, am I right? So he might even be ashamed of the fact that he hadn't met anyone new, and family was visiting. Also, there does exist the possibility that he's found someone new in roughly a week. Fully possible. As a final possibility, he lied about not having met someone to you, maybe out of shame? Sorry I can't be more help, but not only am I not in that age range and have never had a real relationship yet, which is huge, and affects how I'd approach a situation like that, there's also not a lot to go off of in your post. Any more info on this? And I hope I gave you some ideas to think about.