I feel like my girlfriend is overly jealous. We've been together almost a year and that's when I started lifting weights. Girls now give me iois and since I moved into my dorm some of them come and Introduce themselves to me.

Today, my appartment mates had a girl over and she left a note in my room saying " Hey Chinny. This is my room now. Your bros said I could move in since I'm one of the bros too :p" and when I walked in with my girlfriend she got mad and asked "Who is she!?"

It was my first time there (my gf even picked me up) but she thinks I let that girl into my room to put the note there since I didn't lock my door. Then she tells me to lock my door from now on when I leave the room and I told her no.

She grabs her stuff and says she'll stay out of my room after she helps me unpack my stuff. We finish go to her room and lay in bed and her attitude went from" let's do xzy" to " leave me alone, you don't have to stay with me. Just go" and she wouldn't talk.

Knowing she shuts herself away when she upset, I stay and cuddle with her since I figured this was a comfort test. After a while, I changed her mood then she asked me who that girl was and why she left a note in my room. I explained it's an old friend, etc etc. Then she got over herself and went back to normal.

Is this regular girl behavior? Is there a way I can stop this from happening? Shit test or comfort test? What would you have done differently?