hint towards their spotify playlists xuan begins with foreshadow because as soon as he realizes this he immediately tries to find a way to connect himself and vyn so that they can both be happy while vyn starts with fate hinting at the fact that she believes nothing good will happen if she continues down this path and ultimately has to accept the fact that in most cases she will never be happy and runs away from her problems (so xuan chases after vyn's timeline)
and because of the graph original xuanyi find out that they will never achieve happiness because they both exists on differing points of the graph (origin center) (vyn's step mom canonically tells her that she will "be alone" and spend the rest of her life "alone")
one dies one will never be in love and most just never make it anf the whole thing is that original xuan is trying to get his vyn back to his universe and vyn is trying to do the same thing so they meet at least once and then twice but there will be a huge gap where one doesn't exist originally (inspired by sin/cos graphs)