Still any of these excuses doesnt change the fact that she desire it
I don't understand this. Yes, women desire sex.
Part of immersion by a reader occurs when characters do things we do not exactly understand. That's what engages our curiosity and really gets us into a story, we want to figure out why they did that thing that we noticed but didn't quite understand. In writing, "3-Dimensional characters" often do what people in real life do. Say one thing and do another.
They say, "I love you" as you leave for work and then go next door to suck the neighbor's cock all morning. Return home and cook dinner, giving you a chaste kiss with their recently cum filled mouth as you come in the door after a long day of supporting the household.
This game is a collection of NTR fetishes, who likes the genre will see everything. It makes sense that the protagonist is that of a standard NTR, the dumb girl who turns into a nymphomaniac bitch after tasting a big dick.
It's not only a big dick. It's that guys with big dicks tend to have more confidence and experience as lovers. Those alpha studs offer something the boyfriend/husband cannot even if he is handsome and great in many ways. That's why Japanese NTR often features ugly and much older men. It's a different sexual experience for the woman, one which her loving husband/boyfriend is incapable of providing because that is just-not-who-he-is.
The boyfriend/husband is a good guy. He's respectful. He works a lot. He is focused on the family. The lover is all about sex and pleasure. He isn't a good guy. He doesn't conform to the social norms of respect for women (slaps their ass and slaps his cock all over their face while calling them whores).
Btw, I haven't played this game. It looks amazing but I am on Linux and RPGM doesn't work for me (not to mention the map stuff is infuriating gameplay). Waiting for it to hopefully be ported to Renpy one day. I am a big NTR fan.