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Well that depends on the method he used to confirm it. If all he did was touch them and only slept with those over a certain threshold, then that's not much to go off of since he still is attracted to those with no known number and sleeping with someone a few times doesn't present proof of adequate compatibility IF these numbers represent the compatibility of an ongoing relationship and not something sexual.
I'd like to think that the second possibility could be based on "the probability of breaking up" version of compatibility, which means that the MC could have assessed things incorrectly and inadvertently shut out potentially good relationships.
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Um woah using meter as sleeping is kinda unrealistic and I don't think that's what he used here.
But since all of this is hypothesis on both of our part I would like state my belief further.
Since this comparability meter just represents his compatibility with everyone in any sort of relationship(because if they compatibile as frnd then only things will proceed further) When he starts to argue with ml or ml irks him he remarks that the compatibility meter was right. And i didn't think that far ahead, I just believe everytime he mentions how getting along with ppl with less value means he was betrayed in his past friendship kind relationship.
Again it's all hypothesis but let's see what happens further in the story.
0 equals 100 maybe?