Causes in previous lives, consequences in future lives.
When an originally happy wedding ended because another sad girl slipped and fell into the water, the curse of the past life has begun to affect their next reincarnation.
When he was dying in each life, he would recall all the events in his previous life, and the pain of each life when his lover stopped breathing in his arms. Now, he knew that this reincarnation was coming to an end, but he was unwilling to accept the curse of this life, and was unwilling to have his lover die in his arms in every life. He could only beg the old man in front of him - his father in this life.