They Are Imaginary

In Summer seventeen, Cadence spent most of her time in Cuddletown with the other three Liars. However, the ending reveals that the three Liars had died two years ago. In my opinion, the three Liars in Summet seventeen were all Cadence's imagination. Cadence got migraine due to the accident, not just physically, but also emotionally. She was so sad and so painful that her body told her not to remember those things happened in Summer fifteen. In Summer seventeen, Cadence tried so hard to find out what had happened in Summer fifteen. Thus, imagination is the way which helped Cadence to gather her memory fragments. This is one outcome due to her head injury. It makes perfect sence that those three Liars were created by Cadence's imaginary. Just like what the ending shows, Cadence describes that she saw the three Liars swan farther and farther, and they left her alone on the tiny beach. Now because all her memories came back and she had recovered from migraine, her imagination problem disappeared with the three Liars as well. This is why I think the three Liars, Johnny, Mirren and Gat, are Cadence's imagination instead of ghost.