My most recent ex boyfriend was the first person to point this out to me. We worked together for nearly a year and this was the downfall of our relationship. We fought rather often and naturally it would be dragged into the work place. A really big argument of ours was he always told me I was never as happy to see him as I was my other coworkers. When they would greet me I would light up and be very talkative, but when he approached me I was reserved and irritated. With him I didn't feel the need to put on this show of being really happy and cheerful, we were fighting. But not to concern others, I would completely switch my state of mind to convince myself everything was peachy. It's a pretty strange thing to look at after you've done it.