Good intro, you have my total attention.
Nts have a growing demand, so the question is not if, but how to make money.
Well, I can say that NTR genre had big changes. If you look for old hotwifing games, you would see sociopaths wifes\gfs who actually doesn't care about the MC feelings. Also you would see wifes\gfs who were blackmailed and starts a kind of spiral of corruption. These contents are what I will call 'regular NTR'.
After the pandemic, devs started to build games where the couple enjoy the roleplay together, in a harmonious way, without being neglected, but with a lot of fun for both of them. Actually, recent games portray the NTS as a MC's fetish (at least at the begnning).
I think the first step for a good beginning is write a interesting arc of corruption: induce, deliberately or not, the fmc to the nts\hotwifing. Why? Well, if she doesn't need to be convinced it means that she was willing to cheat on you and this is definitely not funny or healthy. There would be no fetish therefore.
You did a good start making the MC feel aroused while imagining Sarah with other guy. But, of course, we will agree that players need more to convince her. A good path is just start with exhibitionism, making the fmc lose the shyness and shame, making her feel more comfortable with the idea of being shared. Please don't use parks like other devs, it doesn't make any sence. Instead, use the beach (not nude beach), pool parties. I would love to encourage her to do a topless. Another way is encouraging Sarah to flert with other men and sharing nudes. Her friends should encourage her too.
I think this is a good step thinking about the fmc in the first release.
But what about the MC?
Explore MC's pov is less complicated, but yet highly important to create a good story. First of all, why he likes netorase? Resume to just a dream looks simplified.
Usualy men in this lifestyle (Sharing) only have 2 interests: fuck other girls (swing) AND\or competition for his girl (cuckolding\hotwifing\nts). Our MC's profile is already clear. But what led him to become interested in the subject is unclear.
Most guys looking for ntr enjoy insecurity. What separates netose from netorare is the fact that the MC have control over the situation, what means that you can trust in your girl because she loves you and she likes to realize you. The most important thing to develop a good nts main character is making him understand clearly his feelings and fantasies. I mean, in the future the MC must be able to answer if he likes to lose the control and being humiliated, or if he would like to play in a more conservative league just sharing his girlfriend. This is what you should make clear for us, the players.
