Basically yeah
He didn't go back in time. He learned memories from a previous life.
The story started during their second life (which is a complete re-do of their first). As they’re bonding, Sejin regains his memories from their first life where he actually did die. Now that the memories have finished, we’re back in the second life where they’ve just finished bonding (which trigged those memories). Hopefully that makes sense!
It's a reincarnation story (they are very popular), he did die and is now living another/second life (with same events as the first)... Ido (in this life) retained his memories but Sejin did not... the last few chapters were a flashback for us and Sejin to their old life, where abuse happened between them and Sejin committed suicide.
There are changes to certain moments because Ido has regret.
Can someone explain to me How he did not die? I’m so confused. He went back on time? I don’t get it