What I find hilarious and frustrating is while Amanda is basically ghosting her father, Moe is the one who seems more conflicted and actually tries to convey his indecision to the MC, by saying something about a moral dilemma that he can't tell the MC about fully. That seems backwards. Moe should be the one giving the MC the cold shoulder, and Amanda should be the one being conflicted by wanting to come to her father about this issue but feeling unable to do so without revealing everything. But we've seen nothing of that. It seems that she can't stand to even be in the same room as him. And again, no, sex doesn't cut it. If she's going to run hot and cold, it would have to be consistent, and at present it's an outlier.
The problem isn't that Amanda is turning against her father at all or even that the aunt is capable of breaking them up. But how it has been handled has felt like a misstep. Even if the aunt presented her with proof, even if Moe supported it, I find it difficult to believe that Amanda wouldn't at least want to get a sense whether her father was hiding something, rather than backing off entirely as step 1. Maybe she tries to talk to the MC but he's always busy training Lily, and then she finds out about the date with heidi or the Lily kiss, and then decides that maybe she can't trust him as much as she thought and begins to trust her aunt instead. And maybe, if we ever get a chapter from Amanda's perspective, that all might be true, except for two things 1- she never tried to talk to the MC in the first instance, and 2- if the player chooses not to date heidi or kiss lily (like I didn't), Amanda has no reason not to trust her father.