Everything went quite smoothly. My interview was on a Thursday and surprisingly, not too many people around. At the security check, make sure you don't have a cell phone with you. [I left mine in the car] And they check you, you go up the elevator, and they security check you again.
Everyone was amazingly nice. So simple. Asked me when we met, how we met and when we were engaged. And that was it! She said " ok your interview is over" and that was the end of it! YAY!
So please don't worry people. it's very simple!! If you're in love and in a real relationship, there is nothing at all to worry about !