Working with insecure girlfriend

So I have a question for everyone. My girlfriend would laugh with me. I referred her for the job because the company is phenomenal and the pay is good as well so it's a good thing for her. She is not the most secure person anyway but she asked me one day before she got the job who I thought was the prettiest girl in the office. Knowing it was an insecure question, I still answered. Now we work together and it's becoming an issue. I waved to a group of people that she was included in last week and got questioned about why I would wave to people. Today we were walking in together and I said good morning to more than one person and as I walked by the girl I said good morning as well. Later on today I was going for a walk with the gf and she asked me if it's normal for me to peak over a cube and say good morning to people. Without the back story, and there definitely is one. I would like you to answer if you consider this normal behavior from your girlfriend. Thanks!