I think it's made quite clear that MC doesn't view Nikki and Karen like the other girls, (obviously they are family members with the patch) both of their first time scenes with him had more passion and emotional weight to them than everyone else.
(Aunt) Nikki was responsible for his sexual awakening, and the tenderness they show one another in private shows they mean far more to each other than just a quick fuck now and then. She says she has no interest in other men after being with MC, turned down Haley when they were alone then only allowed her to go down on her when planning to involve MC. So far in the current version she has only danced for Haley at the club, but remember MC specifically asked Nikki to take her there and keep her busy whilst he seduces Karen, a mission Nikki has been helping him out with that at every opportunity. MC always goes to Nikki first for advice and venting his thoughts and feelings, he clearly loves and trusts her completely. I'd call her a real bro if she were a dude, but 'wing-girl' would be a better term!
As for Karen (aka Mom), well in the prologue I don't recall any sexual tension between her and MC, obviously living together for so long they were very familiar and used to one another just being there I suppose. It was only after they'd been apart for a year that the sexual feelings began kicking in upon MC's return, for Karen at first. She realised how just how much she depended on him emotionally, and felt no need to date or seek company when he was around, but when gone she got so lonely she hired Rosa, and began drinking, even drunk-dialled Nikki one night, prompting her to come stay with her. She saw MC as a proper adult, sexually active man when he returned home, then on meal night when she got all dressed up and showed off that perfect milfy body she'd been hiding from the world, MC began to see her in a whole new light. Initially he was confused when she drunkenly groped him but the seed had already been planted, this woman means more to him than anyone in the world and both felt the growing need to get closer to one another in EVERY way. MC goes more out of his way and puts in far more effort to woo Karen than he does anyone else, there's no way whatsoever he sees her as just another pussy to fuck. His thoughts, feelings, dialogue and ahem, 'physical reactions' during their evening together show how much she means to him, pretty definitively not just another fuck-buddy.
As for the long term, I dunno - MC's a bit of a man-whore but I've read so many mother son romance stories on literotica that I can easily imagine a life long relationship between them.
Haley and MC admittedly do make a good looking couple, but the hints are there now that Stiglet intends to write her out (or at least sideline her), probably due to feedback, also how can she compete with Nikki and Karen, even with that insane ass! She seems a bit submissive so could be kept around in a similar way to Rosa, perhaps to keep up appearances to the outside world?
Even without the patch both Nikki and Karen mean more to MC than the others, but it's far more meaningful (and the dialogue so much hotter!) when you play with the patch!
Ugh, didn't mean to ramble on so much, and I'm probably thinking about it way more than I should lol, it's a great VN, also more Juru!
