My girlfriend eats muffin liners

Today, I baked muffins for myself and my girlfriend, who lives with me. I used plastic muffin liners because they make the cleanup much easier.

My girlfriend has been sick and was resting in bed, so when the muffins were finished baking, I brought them on a plate to her. I went back to the kitchen to finish cleaning up.

Some time later, I went back to check on her and retrieve the plate. I asked if the muffins were any good, and she said yes. I then noticed that there was only one muffin liner on the plate (I brought her three muffins).

"Where are the other muffin liners?" I asked.

"I ate them," she said.

I thought she was joking, so I laughed it off and we talked about the muffins a bit more.

As I got ready to leave, I again asked, "But really, where are the other muffin liners?"

She again told me that she ate them because they still had bits of muffin on them. Apparently she always does this and I have just never noticed.

What the fuck?

I told her muffin liners are definitely not edible (at least not the ones I use). She tried to explain that she thought this was normal and that many people do this.

Am I going crazy? Why would someone willingly eat plastic?

I simply cannot comprehend this, and it has left me a bit concerned for my girlfriend...

Edit: the liners were made out of paper, not plastic. Nonetheless, I am still concerned.