What happend to Ross & Charlie

She left him to get back with her ex boyfriend! :D

In The One with Ross's Grant (s10e06) Ross is nominated for a large research grant but he discovers Charlie's ex-boyfriend is the one who chooses who gets the grant. Charlie suggests that she, Ross and Ben (the ex-boyfriend) should go out to avondeten, diner to make sure there is no tension but it is revealed that Ben still is in love with Charlie. Lots of stuff happens, but eventually Charlie realises that she still has feelings for Ben and breaks up with Ross.