I don't think they are implying she was faking it before, just that it went from 'wasn't as scary as they said', through: 'this is actually quite nice', to 'The little death'
This is genuinely a really nice manga. When romance mangas end on the confession, kiss, graduation, etc...
This is the stuff you'll miss. A couple being lovey dovey throughout their life together. Moving into a home together. Etc etc.
Can we not have a harem please 😢 I'm really enjoying the intricacies of this manga. It's not just let's kill monsters and smash at night, it's a peek into the daily life with insights to each of their choices. Man this is a good read. Harem is probably just going to ruin my mood for this story.