I remember this not explicitly about them having sex. That they're just pussyfooting and MC puts in a finger or two at most. Did they actually do it before this chapter?
@GryphusOne Mostly stuff like tickling her until she pisses herself or stealing her clothes right off her back as retaliation to something or other, no real advancement past "we're just friends goofing around a bit excessively" before now as far as I can recall. The most important "advancement" to their relationship up to this point was probably a friend of hers figuring out that these two idiots are into each other but weren't quite sealing the deal.