Am I the bad person for ending things because of Taylor Swift?

I (25M) met my girlfriend (23F) about a year ago through work, and we've been living together for roughly a month now. From the start, we really connected, and honestly, things felt nearly perfect until recently. We share a lot of interests, and I can’t deny she’s incredibly attractive, which is definitely a nice perk, haha. We’ve always had slightly different music tastes—I'm into indie rock, while she leans more towards the "pop girlies," as she describes them. It’s never really caused any issues; we usually just compromise by either tuning into mainstream radio or taking turns with our favorite tracks. A few days ago, my girlfriend attended a Taylor Swift concert (I didn’t go because tickets were nearly $2,000 each), and while I’m happy she enjoyed herself, it feels like she came back a completely different person. That night, she bombarded me with a ton of videos from the concert, which we ended up watching until about 2 a.m. I got it; Taylor is her favorite artist, so I figured that's just how it goes. But then things took a strange turn the next day. When I got home from work, I was greeted by a life-size Taylor Swift cutout in our living room. My girlfriend claimed she’d bought it a week earlier but thought it was only right to put it up after being "initiated" into the fandom by attending the concert. I laughed, assuming she was joking, but she was dead serious. Now she refuses to move the cutout out of the living room, only plays Taylor’s music on our speakers, and even insists on bringing the giant cutout into our bedroom at night so "Taylor can watch over us." I’m at a loss for what to do. I tried to talk to my girlfriend about it, and she insists I should be happy for her finding something she loves. And I am—truly, I am—but it’s starting to interfere with our everyday lives. To me, it feels a bit obsessive and off. Today, I finally told her that she needs to tone it down and put the life-size cutout in a closet, or I’d have to consider breaking up with her. She ended up crying and mentioned she would enter her “reputation era” if I left, though I’m not even sure what that means—it's apparently another Taylor Swift reference. So, am I being unreasonable for wanting to break up over this? I really don’t recognize my girlfriend anymore.