Territorial Friend

My friend has a habit of getting a little territorial with guys at our job. When she was first hired on, I was on maternity leave then came back right before a big project that took our team out of state for a while. She was great when we were away, but after we got back she started getting a little possessive over the men in the office. I've had this job for about 6 years and have a good relationship with everyone, but for some reason if she sees me having a casual conversation with a male co-worker she'll butt in or if I mention a male coworker she'll try to turn it into a "who's closer to them" competition. She'll even get a little pissy if someone greets me before her or more affectionate than they greet her. I don't understand it. I'm married, so I'm not seeking attention from anyone there. When we go out as a group I sit back and let her grab as much attention as she wants. I just don't understand why she trying to compete with me when I'm not even playing the game.