There will be shitstorm coming up when he comes to remember. He has like disjointed memories which basically made him having 2 different personalities (different from dissociative personality disorder). But because memories were tied up a lot with sensories and in his case it will be more significant since he is very sensitive, he will keep being pulled towards her.
OMGGG
Can say for a fact the earliest version of him with Yiyeon is probably the best one. Even he was jealous of himself because he knows he can't compete with that lol. Yiyeon was too heartbroken afterwards (after all that shitstorm) when they broke up, Yiyeon actually 'buried' him (the best version of Chae Woo) to move on and start anew (another spoiler - she got pregnant). I pity Yiyeon a lot cause she just happened to get entangled with a mess up family that her life was completely shaken. A lot of times she was scared shitless. Chae Woo only comes to finally understand what kind of trauma he has given Yiyeon probably nearing the end arc of the novel. Yiyeon was simply just too kind tbh. Her only wrong move is not telling him the truth from the start. And even if she does personally I think there wouldn't be much difference in terms of how Chae Woo would treat her after he regains his memories.
SPOIL ME IDGAF