fb and other female

Hello girls!
So I'm sort of in this confusing loop. One of my boyfriend's best friends and his wife just came back in town visiting. He got married three months ago, and this is the first time I met her. They know each other since the couple started dating.
So the situation was, we went pick them up at his friend's parent's, and while we headed out, my bf just slightly scratch her head and she meowed back (well, we are all cat lovers!). For me, I think her reaction is way too cute to do to someone else's boyfriend! I will talk to him about how I am feeling, but I feel
like I am being a little bit too cranky about this. Any advice?