I'm just gonna be realistic

Naru is probably going to end up with Sungjoon. That just seems like the safest bet. That said, he shouldn't be with Sungjoon or Somi.

Somi clearly does not have what is needed to emotionally support Naru long term. If she did, Sungjoon's meddling wouldn't matter because Nari wouldn't keep on turning to him. Sungjoon? Toxic. At the end of the day, Sungjoon would rather have Naru get hurt and come cry on his shoulder than build a healthy relationship that takes any time away from their relationship and that is a huge problem.

Somehow, at the end, the fact that Sungjoon has loved Naru for so long will override the fact that Sungjoon sabotaged several of Naru's relationships and even went as far as playing with the feelings of girl who looked like Naru(which was also pretty messed up).

Ultimately, I ship Naru x Therapy but I can come around to the idea of Sungjoon if it's written well enough.