I agree that none of the characters is "perfect," but that is such a subjective standard that it is meaningless. If you mean that the MC must be in a totally harmonious relationship with an LI for her to be marriage material, then I can see your point, but I think such relationships must be quite rare. I've been married for more than 25 years and my wife and I have had plenty of ups and downs, despite everything. If I had to marry only a woman with whom I would never disagree or have any arguments with, I would either have had to be lottery-winner lucky and find someone who is just like me (except with a vagina), or I would never have married.
Having said that, if I think about these girls more broadly I can see where you're coming from.
Of the main LIs, the most challenging relationship is the one with Bella. There's the age difference, which is considerable, the illicit aspect of their relationship which might be exciting but is likely to lead to Bella's getting fired, and then there is the whole issue of Bella's past, her marriage, etc.
The next potentially problematic relationship is with Jill, I think. Jill herself is lovely, but it's possible that her family might try to block her marrying the MC, if they are concerned about their socioeconomic differences. Jill's friends may also cause problems for them, as they look down on the MC because he doesn't have their exposure to culture, travel, fine dining, etc.
Sage is challenging for a couple of reasons: the first is her (step) family, who hate or are at least antagonistic towards the MC, depending on player choices. The second reason is that Sage is graduating and unless she is continuing on to grad school at B&R, will go out into the world to look for a job and get serious about life while the MC is still planning Halloween parties at the DIK mansion. Couples in such a situation often drift apart.
A Maya-Josy-MC marriage faces all kinds of challenges, the most obvious of which is that it would not be legal, at least not in the US. I don't know how difficult life would be if they just lived together, but having children and that kind of thing would get complicated. Not impossible, I don't think, but not easy. And this assumes that the throuple as a unit can stay together. I think the way the characters are written and the story is done so far, they could manage, but IRL? Who knows? The US is generally quite conservative about that kind of thing, so I think they would face a lot of backlash and judgement if they were public about their situation.
Individually, however, I think Maya and Josy are wife material. Maya could be challenging because of her father, but at the same time, he will probably be thrilled if Maya marries a man. MC is already best friends with Maya's twin brother, so that seems like a positive, unless you hate Derek. So I think marrying Maya could be very viable.
Josy seems the most worry-free. Her family is more or less normal, as far as we know, and unless your MC really hates Tommy, the stepbro shouldn't be a problem, either. Josy is sweet, relaxed, low drama. Why not marriage material?
