I love that your approach make you seem to be the Dev's alternate account. However there are a lot of things that may be contributed to a more complex story (Deb as instigator or traitor), junior writer/game developer, or just Dev losing multiple threads he spun.
Deb supposedly loves (be it pathologically or not) MC. Imagine yourself doing things Deb DID to MC in the game to a person you love. Would you consider yourself a good person or an utter scumbag?
- MC sacrifices his freedom and his family life for some moral higher ground (seems like an understandable thing given that he exhibits emotional sensibilities of a vacuum cleaner to his wife and daughter) Deb then uses his wife's resentment of that emotional detachment and the remaining "dangerous" situation to seduce her.
- MC, a broken man, betrayed by the army and by his wife, searches for 7 years to find the love of his life and his child - Deb remains in contact with them, actively helps them to stay hidden and not even only that, but that actively participate in emotional mutilation and manipulation of an underage child. She participates in conscious torture of the person she loves
- MC's daughter (basically an innocent in the whole mess) is methodically mentally abused and manipulated resulting in making herself twisted into a dysmorphic monster (by overtrainig and turning into Stallone). Deb perpetuates the lie that her father hates her, wants nothing to have with her, and has continued his life with another woman. Even if by some twisted logic the separation from MC is necessary for Milly's survival, the destruction of her mind is not - being in contact Deb could have hinted that her father still loves her or something along these lines.
- From the moment MC and Deb are both at Milly's Deb undermines "the person she loves" either to his face, in front of his daughter he needs to re-build his relationship with, in front of his LI. She does that by tearing him down, undermining his authority, being maximally inappropriate, rude, sexually predatorish. Marriages have been dissolved for less than that amount of verbal, physical and emotional abuse.
- Deb forces herself on every female MC seems to have interest in, was or wants to get close. She had no idea the flight attendant was going to turn serious, and has no inkling of Kimiko, but in line with her current behavior she would accost them in the same way she did MC's wife, Julia and Milly before being told by the MC
- Deb has mocked MC with Julia video, with Milly's picture, even when Milly treats her father wounds, she's watching porn on laptop in background???? All signs of affection towards MC for sure.
Only excuse for Deb I can find is hypothetical - the abuse and perversity by he parents in forming years that made her twisted, sick and emotionally unstable. Other than that she is actively working (consciously or not) against MC and his daughter
First, yes the years of abuse are more likely responsible for her behavior, but let's do this.
1. She cheated with the wife, that admitted having a thing for her since before the whole MC getting arrested by the way, and that is wrong, but she cheated with her brother as well so that cancel it-self out, and with the brother, there is no excuse, now can you be mad about it, in my opinion, no you can't, you knew she wasn't the monogamous type, and you yourself used that to your advantage using her to cheat on your wife and previous girlfriends, do I like that they did this, no, I don't, because personally I don't like cheating, but since it happened in-game I can't do anything about it, now for when she did it, would I have? probably no, so yeah kinda fucked up to try and get with someone as they are hurt, but it seems that this is her way to cope, everything to Deb is solved with sex.
2. Again, that is fucked up, I already said that mostly though, she loved both, not just the MC, and the whole idea, again, and I'm tired of presenting this point, again and again, they did it, supposedly to keep him away from what got him arrested and prevent his death, now, was that the best idea? Hell no, it is an awful one that does more harm than good, but that is something that people do, they force a situation "for your own good" without even realizing how bad of an idea, and the harm that it will cause, and a lot of times they will not admit they were in the wrong, that is most of the time the result of an abusive relationship with the parents, that translates to the rest.
3. First, she is not a monster, if you are gonna enter an argument with me keep your fucking opinion out of it(you were rude, so I'll be too, I hate when people comment on others bodies like that, fictional or not, that is a disgusting attitude), now, yes that is fucked up, I never denied that in any moment, but again, that was the mother wishes, if Deb didn't go along she would lose contact as well, so I can see a reason to do so, that is something that she has to atone for, and did you read the story? There is a reason given for this, a dumb reason, but a reason nonetheless, a reason that many parents use in real life, fucked up I know, but true.
4. She undermines him, that is true, and I already answered something similar, but that has no holding in his relationship with Milly, besides making her horny, also, the problem is in how the MC reacts, to what she does, I don't minder being sexual or rude or inappropriate, but the MC needs to have a moment to show that he is to be respected, at least in combat situations, and maybe some more reactions, but my MC is not embarrassed by her, so I don't have a real problem besides them not listening in combat situations, now if this is because you want Milly tp respect the Mc, that will take time, you said yourself she was taught that he didn't want her and has discovered the truth for about a day, this things won't be solved that fast, it has been a week in-game you have to remember that.
5. This one I didn't understand at all, with Milly she wanted to show the MC that she wasn't the only one interested in sexual contact, it was mostly to prove a point. With Julia, it was a "Look what you are missing out in, idiot" because if you played the game they invited him to a threesome, and the MC denied, I have already talked about this, and I wouldn't deny it and wish we had a choice in the matter. This for me made no sense, so what that she is watching porn? They have seen combat, some bruised ribs were what a got in training practicing martial arts, it isn't a big deal, also she has zero sexual hangups and is more of a friend to Milly then aunt, they were talking about that before the MC showed up and only continued after, that is it.
I have to find a way to link to this next time, I'm done repeating myself.
Edit: Also, no I'm not the dev's alt account, I don't have enough will power to make a game consistently, sadly, because I do love programming and writing stories.
Edit2: About the undermining:
https://f95zone.to/threads/triple-ex-v0-05a-azrayal.39943/post-4013632
