Is something wrong with my game/savefile? Or am I missing something?
I'm going to bet that her arousal isn't very high.
Give me a moment and i'll grab a few screen shots and edit this message with them so you can see what I'm talking about.
Edit:
I'm not able to reproduce this (at least w/o editing my save/variables i think). I was able to grope her in the morning at 0 arousal, but at the same time I've completed her content in that save. It seems like something has happened to remove or unset a flag? I'm doing another run through to the point where I get that option unlocked the first time to see if it triggers a flag in the save file.
Edit 2:
I'm just guessing here, but it seems that option is tied to Questline_Misc or potentially Questline_Main. Based on the hint before it becomes an option, it's tied to being able to study Computer Science. Once that becomes available Main increments to a value of 2, and Misc is created at value 1. However, the save I made while at the choice prompt has Misc at a value of 2.
So, try loading your save on saveeditonline.com and find out what the values for Questline_Main and Questline_Misc are. knowing that will probably help figure out what's going on, and if you did edit the save or variables, you should say that too so that the dev doesn't waste time looking for a bug that isn't there. I've done the same thing (managed to get self_control to a negative value and thought it was a bug with the new content... i'd manually edited it to a value that, based on the game's coding was impossible to achieve and bugged chasmalim about it in the PM before I posted the cheat method.)