What is the main point of this film? What's the ending

In the late 1980s, Hu Bayi (Chen Kun), Wang Kaixuan (Bo Huang) and Yang Ping (Shu Qi) tried to wash their hands of it. Mo Jin, the once all-powerful captain, became a street vendor and was chased all over the street by the immigration bureau. Hu Bayi and his fiancee Shirley moved to the United States and lived a normal life from then on, but on the eve of the wedding, they found that their first love girlfriend Ding Sitian (Angelababy) who died in the "Hundred Eyes Cave" 20 years ago appeared again! Hu Bayi, Wang Kaixuan and Yang Ping decided to re-enter the Millennium graves of grasslands. The ending is that the flowers on the other side are broken, Ding Si dies sweetly, and Hu Bayi, Wang Kaixuan, Yang Ping and Dajinya escape from the ancient tomb.