Thousand Years of Love: the Emperor's Palm Pet

The three realms are divided into heaven, human world and secluded ruins, and the balance is maintained by the "way of heaven". In ancient times, there was a war between gods and demons, which sealed the "Heart-Eating Demon Lord". His soul was scattered in the world, and it would take thousands of years of reincarnation to reunite. What maintains the seal is the "chain of destiny" - it can only be maintained by a pair of destined people using their love as a guide and their hearts as a sacrifice.