People man. Most likely children or people with mental disabilities, getting assmad about fictional characters like this will never not be funny to me. I enjoy Arato, hes the inferior asshole and a good plot decive. Jobber-tier sex machine, you can do a lot to mold him narratively in order to make him both inferior to peak Satashi and Kendo. Thats to say, Kendo has so many flaws which he realized himself as part of his personal growth. He already got what he wanted though.
Satoshi losing Mary to two cringe overlords sounds like a total win for me regardless. Its Marys loss all across the board not wanting a cute, high tier hubby like that. He may not totally live what Mary has lived through, yet has a deeper connection to her than Kendo and Arato ever could.
I like Kendos gradual climb towards becoming a real man however. And that includes showing some goddamn self respect and humility. Best way to end this is to give Mary the chance to fuck both Kendo and Satoshi at once, then deciding who is better. Satoshi simply lacks technique and stamina and its already lore that you simply have to press Satoshis buttons in order for him to have a days worth of sexual stamina and being able to have sex for 12 hours straight. Pretty sure the same applies to him learning about proper sex techniques just as much.
The writing in some ways is fucking god-tier. All of the whores in this game slowly do begin to realize that dick size matters secondary. Arato and how bad he actually is as sex but hes great at mindgames and dominance with a hint of sadism. If you somehow can fill the gaps with Satoshi learning to become a real man while still being a good husband, then this is a stomp.
Satoshi right now is that narrative empty state/goku. We don't know how good he actually can be in bed, but we know that Satoshi was realizing a fraction or so of his full potential before the story took place. We already saw indications that he can man up to an extend that makes Mary sweat, while before she couldn't even feel his dick. Once he drops the training weights and get some proper tutoring then hes good to go. Right now, for most readers, Satoshi seems so meek and weak because hes in an environment of pathetic show offs. Meanwhile, Kendo did imply and say that he always wanted to be a relyable man. Satoshi may as well become the substitude of a son figure. I'm probably not correct but I can see that the author probably played with this idea already.