Why cant Caiyi stop thinking about Meng Renshu. No matter what he says he was one of the reasons she died. Why dont Caiyi just move on???😡😡😡

I can't understand what Caiyi is feeling guilty about all the time, when Meng Renshu is involved?? What has Meng Rebshu's illness gotta do with Caiyi? Ziqiang is her boyfriend so no matter what she should stay away from Meng Renshu.