This thread is ancient, but you linked to it earlier from another thread today or yesterday, and just *wow* I'm glad you did. For me that scene is always just a whole lot of uncanny valley, and mad props for putting that feeling in well-defined terms. I hope to anything that this feedback has been understood.
I think your points about committing to softcore or explicit are spot on, and given that we're still lightyears away from photorealistic humans in games, the softcore approach is probably safer from a reality-holding-together perspective.
The game with some of the most realisticish-feeling romance I can think of is Pillars of Eternity 2. It's very gradual, unfolds throughout the story, and is entirely text/dialog. Your term battle-fuck is great, and that's been my reading of Minthara's motivation; also, event without the battle sitch, it doesn't seem unrealistic to me - I know people who go from 0-60 in a heartbeat, and the way Minthara turns is totally justified because tadpole.
Again, this is really well done, clearly took a lot of time, and is 100% spot on.
