The LN doesn't go there. Also, how is this NTR? She's not "his girl", he's a commoner and her butler. Social circles would say that he was the scandal and Grant was "the socially acceptable choice". He has to say "no" to her at this point - that's the whole point of the story. Towards the end of Vol. 1 of the LN, MC squares up against Grant and kisses her. This chapter is probably ~2/3rds of the way through the first volume and that kiss is just about the last thing of it.
Also, Grey's sister shows up in volume 3 as a teacher from an institute/university/etc. as the one to educate him in the ways of nobility or whatever (not-really-a-spoiler alert: he marries and has chlidren with Alicia at the end of the series, Vol. 3).
There's some tedious "incest bait" there but genre-savvy folks understand that's also not the story.
Also, if this chapter is ~2/3rds of the way through the first volume, and there's possibly ~3ish more chapters until the end (just a nice round number), that's another year of waiting for this LN volume's adaptation (at this rate), and if the next two LN volumes are also ~15ish chapters, that's another 10 years there for both of those. We're gonna be waiting a moment XD
I wonder if they'll instead just end it at the end of this volume and say "buy the LN"?
