Well, I'm afraid I have to upset you, because any serious relationship is destined to failure in a long shot in this VN:
Lucy - will always look back at her sister, fearing charming Charlie, that she'll seduce and take the MC away from her. Even if not her sister, then another woman whom she'll consider more beautiful than her. She is very jealous and uncertain, and suffers from it...
Charlotte - is afraid that the MC will leave her, just like the father of her daughters. She thinks the MC is next to her because of the money or her beautiful flexible body... Sticky fear and vague doubt will chase her constantly. In real life terms, before having a relationship with the MC, she needs a very long period of psychotherapy, including a sexologist. She will be avoiding intimacy with the MC by all means.
Suzi - will fight with the MC for dominance in a relationship regularly. Her attitude towards men is ruined for the rest of her life by the leaving of her father. Her way out now is a long-term psychotherapy or a homosexual relationship.
Emma - with the leaving of her father, she lost his love. She is an half-loved child. In all relations with men, she will look for her father to fulfill her whims, desires and impulses, and he should treat her like a little princess. She will be attracted to such a type of men, she will not look for an equal partner.
So, they can’t develop a healthy relationship, unfortunately. This VN is all about drama.
Her cheerfulness and playfulness are a shell or a shield. She hides her pain, grief, sadness behind playfulness and jokes. Her tears mustn't be visible to anyone, the mask of the jocker hides them. She is pretty aggressive towards MC in the sense that she goes to various tricks - she ran her bare foot along the MC's leg, or she exposed her peachy ass, then her chest. She plays out the same scenario - pick up the guy before he pays his attention to Charlie. So, she doesn't behave "right".
I like the way you pinpoint the way they behave, and I actually agree with your assumptions, they all deal with trauma in some capacity, all of them, and I'll include the MC in all that, cause it's the same for him, he has the same conflicts with the actual Emma than with the former one, but he made the whole situation his redemption, it goes deep.
What I disagree with, is you final assessment, I don't think they can't develop healthy relationships, cause I believe everybody can heal, sometimes even without professional help, they just have to accept they have problems, first and foremost.
Charlotte sees, while we play, and if the MC gives her space, that he's a good guy, she's tormented by her attraction, but she pushes through it nonetheless, cause she felt, for the first time in decades, safe in the arms of a man. Yeah she's conflicted, very understandably, her flashbacks are sick... and while I never went through what she went, I've dealt with past traumas for most of my life, sometimes it's trivial, you just need to understand what 'mental switch' you have to press, at other times it's more complicated... I think her inner conflict is well-written, conflict there wouldn't be at the first place if he didn't treat Emma right. (also, I didn't fool around with Lucy, nor with Kaylah, so I suppose it helped, my MC isn't a 'pig') As long as the MC give her time, if on her path, she'll open long-locked doors.
Lucy, absolutely, the black sheep, the 'lesser child', the one in the shadows, always left behind or tossed aside cause she isn't the 'one'. Deep wounds, she will have to deal with her youth, with her 'inner child', for sure, cause yeah, you did pinpoint her need for attention, her aggressive behavior toward men. She deserves someone in her life, but as long as she doesn't deal with her youth, those relationships will falter as fast as they came. She has to see herself, and love herself, first and foremost, my MC rejected her twice, don't know if that's what triggered her inner turmoil, she's self-conscious. She also has to understand her life isn't defined by her sister.
Suzi, yeah her hate of the MC, her outbursts of rage, and otherwise the way she weirdly objectify herself, I think you're right, there's something against men, and yeah, it probably stems from her abandonment from her father. Can't just comment more, cause we only see her a couple times, she needs development big time.
And Emma, yeah, she's 18 but acts like she's 12... her emotional development, from being overprotected all her life, really, -really- is stunted, she isn't stupid, far from that, but living in a 'fairy bubble' will absolutely give you a false perception of things around you, especially when confronted with how things actually work when you're 18. In her case, like you said, she wants to be treated like a little princess, exactly like everybody around her does, I mean, it's the only reality she knows, but she'll get in trouble big time everytime she has to deal with the outside world, people will bully her out of envy/jealousy, jerks will try to use her for their own benefit cause she's an 'easy' target (like that bitch, Zak), and depending how we treat her with our MC, I guess. Innocence, purity, sadly those are rare traits predators look for. In her case, perhaps Jenny will actually wake her up to the real world, cause it sure won't come from the people around her.
Whenever I feel an AVN has the right amount of psychology in it, I kind of feel inspired, so pardon my long reply.
Like I said, I agree with your 'worst-case' scenarios, I just don't think it's as doomed as you seem to think, I think there's a possible 'redemption' for all of them, and perhaps a real one for the MC. Peace.