@punyemas this is a spoiler- in the novel it is stated that these two share so many regressions. In one point of time they where married and even had a kid. But somehow the time they spent togather always end as Gu dies every time. The girl has the regression ability and she uses it to save hom each time but never succeeded . So this time she gave her ability to thr mc so he can regress . She can no longer regress.in the forst chapter she was looking for her current fiancee becuse he actually had a way to help the demonic mc .she got angry because the mc thought she was looking for fiancee but actually she just loved him. Thats why she was crying failing to save him