Near the end of ch 55, the line "do you even know how i came to receive these feelings" makes me feel like there's something more to why sungji fell in love with sumin.

plot twist (and also a long shot), sungji actually met sumin years ago, probably during the time when sumin was in the hospital or some sort (which puts sumin at 24 yo and sungi at 14) and sungji remembers her from some act of kindness or sth.