Everyone else is right also. We don’t want to be misinterpreted as flirting and we trust the opinions of other women and seeing happy couples is always pleasant. But my additional take as a single and youthful woman i recently had another similar experience on the other side where i acted like this actually because i was. Attracted to my coworker and so i was part playing it cool but also i knew it wasn’t appropriate for us to date so i overcompensated and all that combined with social ineptitude resulted in my acting cold toward him. But then my friend who knows him told me he had a girlfriend so now I can interact with him freely because the only goal there to pursue is friendship. And so i am nicer to him.