hey girl....chill...quit all these nasty thoughts....he is a human being and meeting new people and adding them to his facebook.....don't get obsess with such a small tiny thing in life....he was single that's why he got on the online dating to find somebody....it's difficult for guys same as girls to find a partner.....he posted that he's in a relationship with you, that's awesome....just my question to you is that "who initiated the request for the relationship?" you or him?

take it easy and if you feel angry or sad just don't talk to him at those times.....

M.