I don't know how the dev will handle it. Either he makes it so that she was lying to the mc about that (at this point, I don't even know why she would lie about that), or he just goes through with the whole thing.
I would assume she lied to the MC in an attempt to push him away. Her whole character, in what has been released so far (up to the end of 0.3), has been about pushing people away until/unless her situation is otherwise hopeless. As of the end of 0.3, MC has given her very little reason to see past her own rough past, just as others don't yet trust him. Those who have reason to trust him have had him earn it (albeit in the usual fictional-story-enhanced-rapid manner and pace).
The full context/quote from KS can be found in this Patreon post:
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Then I started to realize that such a backstory is a much needed breath of fresh air considering how many backstories are similar across games.
Far too many devs/authors write basic backstories, or they fail to use backstories to justify why characters act like they do. Everyone has a story. Everyone has a past. We, individually, aren't actually in the story, so there's no stake/risk in exploring it. Given that the design of New Horizon appears to be as much about exploring the past as it is about people growing together, and particularly given the 'harem' tag, I'd suggest that the story would be poorer for those who skip out on her content.
If people can't get past the discomfort of going through her story with her, that's their choice, and there's no reason anyone should hold it against them. Though, on the same note, there's no reason for them to keep bringing it up unless they're looking for people to hold it against them (either long term, or short term in discussion pushing back against them). Maybe that's their kink, but this is the sum of my weighing in on this.