So a CRAZY longshot here, especially since I don't know what else you have planned for the game/story, or how much more, if any, you plan to implement.. But what if that blue dildo scene was made into something more? The whole breaking the wall and changing her mind thing had me thinking...
Like what if it was something that actually benefited her as an "upgrade" in some way.. For example, through means of magic or "science" (lol) or whatever - it actually mutates or warps her body.. magically shifting her guts around it and making it possible for her to miraculously be able to live through 'basic' impalements, by slowly impaling her as well during that one blue dildo scene, literally changing her physiology.
Then from that point forward she's immune to regular wooden impalement stakes.. instead now quickly and fully impaling her when they touch her but only making her simply moan with pleasure and then letting her go, or if she's low hp it causes her to orgasm instead, holding her up from moving briefly or something, but not killing her, no blood, no damage, etc.
And then add new impalement devices that are like larger, different materials, spiked, etc... Spiked one still fully impales her immediately, and she lives.. but it causes substantially more damage than any other ones. Metal ones come out of her chest instead (or impaled horizontally through navel or something) and still kills her at low hp like the original one did (preferably making her look down at her chest in utter shock), and larger/wider ones, or maybe barb hooked ones, get her briefly "stuck" on it but don't kill her - however, making it so enemies can come and maul her to death if she doesn't get free in time.
This way any backtracking to areas with the basic wooden ones would be easier too, and you could even design some enemies that brutally fuck her "all the way through". Which personally I'm a enormous fan of and so far the impalement is my favorite part :)
I know it's all extremely far fetched... and likely doesn't mesh in with your plans, but I think it could be really interesting for the game and in general if she gets "upgrades" like this from time to time. Like for example another scene later on where her throat is fucked by some enemy or mechanism that "installs something" which makes her unable to be decapitated as easily. Or something else that makes it so she only moans/orgasms herself back to higher hp if she gets attacked by weaker enemies, introducing stronger new ones that rip her limbs (and tits!) off at as her death scene or something. A lot of designing/programming to be sure and maybe just too much work, but I've got tons of ideas like this if you're interested
If nothing else it's something to consider, you'd be a real boss for going against the grain like this for this type of game, even if it flat out makes no logical sense LOL. That's what "magic" and "science" part is about anyway. And there's already something really mysterious going on this forest, completely changing people, after all..
EDIT: Just wanted to say too I freaking love the game btw :) Especially the fact that they're all musclebabes! Very well done