Why doesn't Rey kill herself?
Most of her loved ones are dead - Leia, Solo, Luke, the love of her life Kylo Ren, her parents. She'd become a ghost and could hang out with them, and would still be able to interact with those who are alive.
She could settle down and have a nice ghost relationship with Kylo Ren, or do you think they might fall out over the fact she didn't bother to bring him back from the dead after he did with her?