Most of us move on from the "copying" phase of development by the time we enter kindergarten. It can be frustrating being a 6-year-old whose 4-year-old sister won't stop doing exactly what you do because she wants to be you so badly. You beg your mom to make her stop copying you, but it doesn't help. She still claps when you clap, puts a bubble in her mouth when you put a bubble in your mouth, and generally annoys you until you can't take it anymore.
Once you grow up, you notice more subtle forms of copying that happen out of habit. One of my best friends adopted "Hey princess!" as a greeting, and now I literally can't stop saying it. I don't know if I adopted the phrase because I think it's funny, I spend so much time with her, so I hear it all the time, or I'm prone to picking up catchphrases, but whatever the case may be, she has no problem with me copying her, as I have no problem with her copying me and my silly slang. It's not like I'm acting like I coined the phrase first!
Many other forms of copying can make a friendship weird. If you start dressing like your friend, talking like your friend, constantly checking your friend's location on Find My Friends, and thinking about your friend more than anything else, you might be experiencing limerence, or some other kind of obsessive thinking. While it's normal to feel very affectionate towards your friends, you shouldn't be as enamored with them as you are with a romantic partner. Even being obsessed with your romantic partner can cause difficulties in your relationship.
The woman in this story is struggling with her friend being obsessed with her. It's not only ruining the friendship, but it's adding more stress to her already stressful life.