I think it would be best for sungji to be with dawoon rather than sumin. And from what i seeeeeee (if my insting correct) sungji have a feeling for dawoon all this time. But there's still so many mystery of their past for now and i cant wait to know it.
Sungji always geting flashback of the moment when she with sumin i think that was normal, not like when sumin getting a flashback of seju when she is with sungji.
I cant think how sungji and sumin will work out without seju getting marriage or die in the end. But now dawoon comes and i think this is the best way to make every character have a happy and healing story. Sungji gonna forgive sumin but not to be together anymore, and sumin forgive seju too. Maybe 'healing' means for them to forgive each other.
Sungji end up with dawoon and sumin with seju. Well typical korean drama and for me its not a bad thing to turn it that way. i am #teampink and i dont want to see seju died or getting married or ended up with nami.