To those who doesnt understand the movie.I will explain it here.

Spoilers ahead!!!!

Lin Bei Xing in this movie is another version of Lin Bei Xing. So we have Movie version Lin Beixing and Drama version Lin Bei Xing. Both of them are living in different universes. So the drama version of Lin Beixing was not here. We only have Zhang Wan Sen and Lin Bei Xing movie versions. No drama versions of themselves are not in this movie.

First, lets start with the fire incident.

In the original universe of Zhang Wan Sen movie version, Lin Bei Xing died in the fire incident. Then he cross parallel universes to save Lin Bei Xing. (This is the only ZWS that can travel in parallel universes)

While in the original universe of Lin Bei Xing Movie Version. Zhang Wan Sen is the one who died in the fire incident.

So both movie versions are not in their own universe. ZWS and LBX movie versions are both travellers and not in their original universe.

Lets name the movie univese as "Universe M"

So in the story, both travellers have cross paths in the same universe which is Universe M. They have both have the same plan, to save the other in this universe.

Only LBX have a restriction in her travelling rule which is "Dont let him says his name to you or says his name".

While the restriction of the drama version of LBX "Dont say I like you to one another"

While ZWS movie version have one restriction that he doesnt know because its the first time he travelled in another universe. His restriction was "Dont introduce yourself or say your name to LBX".

In the case of movie version of LBX. She already travelled several times, thats why we have different versions of ZWS in her POV. She will come back to her own universe if she says his name. (Reminder: The ZWS in her original universe is confirmed dead)

She only have one chance left, and that was universe M. Where ZWS in this universe was really similar to ZWS of her original universe.

The ZWS in Universe M is also a traveller like her. So both doesnt own this universe.

In the end, both have tried to save each other. In universe m, both have reported the concert so it will be cancelled.

So how did both of them know that both of them are travellers.

ZWS learn it when he was listening in the car after hearing LBX story on the radio.

While LBX knew it from Maizi. ZWS told Maizi about what happened and told him that he isnt the real ZWS in universe M and LBX dies in his original universe.

Then both of them met knowing that they arent the real ZWS and LBX in universe M.

Since they dont own this universe, they have to go back to their original universe. They feel guilty for owning a universe that doesnt belong to them. So when they return to their original universe. The real ZWS and LBX will be together.

So happy ending? Yes, for the real ZWS and LBX in universe M are both alive and are together.

But the ZWS traveller and LBX traveller didnt have a happy ending. Because in their original univese, one have died already. And both came back from their original universe.

In the end credits we see the drama version of LBX. She is in her original universe and we can finally see that ZWS in her original universe didnt die. So we got a happy ending for the drama version of LBX and ZWS.

Thats it, the whole universe was against this two. Most versions of themselves in every universe had sad endings but there is some universes where other versions of themselves had happy endings such as the original universe of LBX drama version.

This is literally, I love you in every universe.