This IS cheating and netori (stealing a woman from another man). With a tiny bit of netorare in the end.
But, definitely, this isn’t the evil, lame-ass, typical story I was already expecting. Hey, to my surprise, that was good ^^
It’s easy to sympathize with the characters, including the male MC who isn’t an evil mastermind but a young man driven by sheer titanium-solid will, there’s a light comic relief ambient atmosphere, and the girlfriend-stealing was presented as the inevitable outcome.
To summarize it, hmm… Let’s begin with the manga classic, a promise between children, and ten years later, they meet again. The boy kept on believing in that promise, the girl totally forgot and shrugs it off once she’s reminded of it: “are you dumb?”.
And yet, for reasons (that will include superior sex technique and lasting longer than 3 minutes, who would have thought, right?), in the end, she chooses the better lover ┐(￣ヮ￣)┌
I’ll insist, it’s not “ugly”, evil or anything, I think. And the drawings are well worth it. Usually horribly censored, huge warning, but every part without the censorship is original and splendid eye candy 
Release credits are for Obsolete Zero, with PaGe422, GMan, Kopkill11 and Eroyama, thank you! 
By the same artist, I also share Shishite Netorare.
