Personally I think that NTR games, or rather GOOD NTR games are hard to come by, so it's easy for these devs to pick up a decent following when they put effort into their games. However they realize that a solid amount of the intensity, comes from the lead up to the big moments. The first time the MC's girlfriend/wife is touched, first time they suck another guys dick, and of course the first time they have sex with another guy. Knowing that this is where the big appeal is, they realize that milking those feelings of intensity between each key moment results in the highest retention of players. It takes a good writer to keep an NTR story engaging past the initial moments of intensity and they most likely fear stagnation after we finally see Rina having sex with Kenji.
In a way I get it. It does get hard to make it work, because eventually seeing the girlfriend/wife fucking the same people over and over gets old. So to curb that it usually means upping the stakes over and over. But that also has a ceiling to it as well so it takes a careful hand. The Adventurous Couple is an example of a game that's hit that ceiling and is now trying to find ways to make it engaging without just constant raising the stakes and increasing the sex scenes.
Off the top of my head I can name a few that have managed it without getting stale.
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did a good job of telling a NTR story from the female POV, and having the female lead going more and more insane as she NTR's the protag as a means to try to keep him to herself. A good netorase game that is told from the male POV that also kicked the trend was
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, which has the male MC infected with a virus which makes him only aroused by getting cucked and isn't the typical "Wife leaves you for big dick" type NTR. You could even maybe say
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is equally as good at being incredibly engaging, but the NTR in that game is for sure not the main focus. Tho the last couple updates have been centered on flushing out the NTR arc.
All this to say, the dev is for sure milking every cliff hanger they can for the paycheck. But part of me understands their struggle, because surely once they have Rina fucking a bunch of different guys, the impact will lessen and numbers will most likely drop, unless they can tell a gripping story. And so far, story writing hasn't really been this dev's strongest point. It's pretty much run of the mill office worker getting off to his wife having sexual encounters with both his boss and his Wife's friend's son. Nothing really to it besides that.