It isnt anyone's fault....n Gunji to not at all!
She is a simple naive girl...n no one ever except for her family has cared for her so much
It is jus natural for her to develop feelings towards him as he treats her sooooooo nicely n makes her feel special which no one has ever done before
Sammy always does things for her dat he doesnt do for anyone else...so she is gonna think dat he also does consider her special somehow n cz of dat he is doing all this
N its not Sammy's fault either since he's never been into meaningful relations so he simply considers Gunji his best friend....he doesn't no the relationships beyond friendship...n so it wud take him time to realize that No Gunji is something more than a friend!