It'll be funny if he doesn't have the motivation to start his journey to save the world, and Laura ends up being the one to save the world.
Lukas didn't really do anything significantly wrong, in the game or the current life. The worst thing he did in the game was to be unclear about his feelings when he left town. That's like, "could'a done better, but not really bad either." In the reincarnated life, he's basically still a kid.
Laura hasn't really done anything significantly wrong either. Sure, she could be handling Lukas with a bit more care, but it's not like she's in the wrong to want to see other people. I mean, she's technically just a child with a bunch of new memories, so it makes sense she's not gonna be super mature about it.