There's no issue with those big sisters, his mentors, etc. This was one my fav manhwa before as well.
But Im TIRED of damsel in distress. Let's just say it's easy to detect the author's intention during the first few interactions and the characters' response to MC's action.
Maybe the author doesn't intend to proceed with it and changed the interactions afterwards, but am I obligated to read more and be patient for the character growth?
If u think when someone said HAREM, it automatically means MC MUST romance them for it to be so, then think again. My tolerance is low towards all these hints especially when it involves damsels in distress. It's tiring and annoying. Im a girl myself and all these feels insulting.
This is something I'm personally feeling disappointed about with this manhwa, that's why I didn't rate it. And only expressed PERSONAL disappointment in which I believe I have the freedom to express. (=・ω・=)

I left at 117, and came back to find out it became harem? Wow the disappointment man.