It's only at 53 chapters. The official raw uploads each chapter in parts and these parts are each counted as one. You can see the actual chapter number in the name.
I'm a bit confused.
He walks in on her holding her panties. She says he has "seen it before" but then proceeds to talk about him showing off his underwear.
The "you've seen it before" made it sound like he has seen her panties before.
I thought this too at first, but it does make sense the way it is.
He's giving her a massage, she likes it, he uses the excuse of stagnated lymph flow to touch her boobs, she gets "angry" at him but doesn't mind it, he apologizes.