Controversial ACGAS opinion, but I totally don’t ship Tristan and Maggie. We know so little about her as a character - she’s always on the fringes. Whereas quite rapidly, we’re given deep insight into Charlotte and why she and Tris are so well-suited to each other. In the very first real conversation they have, we learn that they both have been “over there.” They both have been forged into adults by experiences that no one else at home can quite understand.
In fact, I see in Tristan and Charlotte rather a mirror of Siegfried and Audrey - both reflecting and inverting certain elements.
All four of them served in their respective wars - all four of them escaped some aspect of their upbringing and came into their own while serving. All four of them carry both honor and scars.
On the surface of it, Siegfried and Audrey are a reversed Tris and Charlotte, at least as regards apparent societal status. Although, in reality, Siegfried and Audrey are much closer together in social rank.
Despite what many people say online, Siegfried is categorically not a gentleman, in the traditional English sense. That is to say, he’s a professional man who very much works for a living - through rather hard graft, at that. Culturally, he has an aura of the upper middle class about him, but economically, he’s a man just about hanging onto middle class life in an out-of-the-way hamlet in Yorkshire. He’s likely no more prosperous than the butcher, the baker, and the candlestick maker - the nation of shopkeepers. Audrey’s clearly working class background is below his, but not dramatically so: particularly as we know she’s an educated and highly literate woman, in spite of her humbler occupation.
Tristan, of course, shares a class status with his brother - with the added minor indignity of not owning the house or the practice and, as he says, sleeping in the spare room. Charlotte, daughter of the landed gentry, is on paper much further away from him than the Farnons are from Audrey. But, as she clearly states for us quite early on, this isn’t a matter of great relevance to Charlotte herself.
In both cases, despite a seeming inequality between the partners - in one case with the woman lower, in the other case with the man - a commonality of feelings, experiences, maturity, and patience with one another exists. I think that that added depth we have in Charlotte, the things she and Tris can share, is so much more compelling than his old teenage, back room fling with Maggie.