Aww, you picked the nicer options for him haha. I would always suggest experiencing both choices whenever you can (by saving). Most of the time, the scene isn't impacted much, just slightly different dialogue - but sometimes different information is shared, or different actions are performed. For example, in chapter 16, you can choose to chew him out, or accept that you could have been nicer. The first choice gets both Neil and the MC all riled up, the second one Neil apologizes again and he gives some sort of explanation to his behaviour.
Koakuma? I had no idea it had a term, but ... of course it has a name. It's a reoccurring trope (I'm no fan haha). I don't think there's many types in otome games where the MC can actually tease the guy, it's pretty rare.
Dimitri will still have moments where he's wearing his glasses (mostly at night). I have one really hot CG planned for him with his glasses on ... :D
Actually I just realized all of my CGs of Neil are basically him being caught of guard, and Dimitri gets all of the ... aherm ... steamier ones. I think this is a reflection of my own tastes ahaha.
Alright, so you were simply playing the game and it closed on you - I think that may have to be your PC as well. I really hope you'll be able to play future installments, as each update will get progressively heavier on RAM.