You're very possibly right, although sometimes one response of a set will give you affection or lewdness with a girl while the others do not. I wonder if you were to gain practically neither of each if the event chains would be different. I suspect not, but if that's true it begs the question, why even have menus in the first place? As a sandbox, you can literally just completely avoid a girl (except for group events or maybe very specific other occasions), so the menus wouldn't funnel you to anywhere in particular. I don't think I actually even know what the points on girls do in this game.
There probably are some conditionals for slight variations in scenes, but it feels like the same things will happen mostly, regardless of what you pick. It's a little curious, if I'm honest. So, like you say, it's extremely kinetic in nature.