It's a metaphor

If your a fan of the fault in our stars than read this. It puts you in the story and in the end you fall in love with Augustus and he with you
Some background:
F/n l/n always thought the concept of death sucked. She has an older sister named EvaRose. Eva has cancer and y/n being the worrier she is only focuses on trying to help her sister. One day Eva asks y/n to go with her to support group, where she meets Augustus Waters and Hazel Grace.