<human>: Pretty long, but please.

I've been dating my girlfriend for about a year and a half now. We are both +15 and get along very well with each other.
Unfortunately, I introduced her to a rock band in the beginning of the year. Now I seem to find her obssesed with them.
After a week, she "loved" them, she posted FaceBook statuses about it, she even bought a concert ticket which was the following month.
Even worse, she now "loves" the lead singer. She tells everyone how she's his "boyfriend/baby." It's been two months since she has known the band.
She actually jumped on stage and kissed the singer (YouTube video, I saw it). She actually has his name always written on her wrist or finger. She actually bought an autographed photo on eBay along with a shirt of the singer. She actually obssesively loves him.
Now I find this very bothering.
When we hang out in lunch, and I see that she has his name on her ripped knee jeans, it changes. My mood, my feelings, my thoughts.

I don't find myself to be the jealous type... but I could be wrong. People in fact tell me, "She is obssesed dude!" "She is all up on his sack bro." "Does she even love you?"
Now statuses about him: "I love ______ so much!!! <3 :D"

In addition, she has a cover photo of him on FaceBook; instead of a photo of us.

The reason that I said "Young boyfriends" is because I do not feel that older boyfriends go through this. They are mature.
Along with, Justin Bieber....Disney boy bands, it obviously attracts young girls; and young girls have boyfriends.

Please, if you can..... what should I say? How should I handle it? Should I ignore it? Should I forbid her to say anything about him? Or should I just let her be that wild teenage girl in love with musicians. Please.

Can you condense the text into a few key points?
<bot>: Girlfriend's in madly love with a band's singer. IN LOVE. It bothers and annoys me. I want feedback and opinions. I beg of you Redditors.