Tsuki's perspective makes it look like her life followed a very expected trajectory towards a "failure", while also making it look like Sora was set up to end up successful. Whatever happened on Sora's side for her to end up in the same exact position as the expectedly gloomy Tsuki could end up...
She's been asked if it's okay after every escalation, agreeing to it, and we literally see her internal monologue about wanting more. As I said - unless lady's magical pheromones have actual drug properties which completely clouds Risa's judgement, she's been very consenting to whatever the fuck...
Even if she's not even close to a relationship with MC, Risa going from "I actually like this guy fr fr" to "let's just have sex with this lady idc anymore" in the span of 5 chapters is jarring.
But also MC's massage powers are on the magical levels now so maybe this lady's pheromones are also...
The reason why Miyuki could never atone no matter what she does is because her actions make no sense in the first place. I guess the author didn't want to make it an actual ntr story, so we've seen nothing of their relationship with MC and we've seen nothing of her relationship with the Kondo...
Man I really was somewhat expecting(hoping) that the MC is actually dealing with something serious behind the scenes and all his deadbeat behavior is an act, but he is just pathetic