The Prime Minister by Anthony Trollope
There are two themes: politics and the position of women. Politics hasn't changed much (I underlined a bunch of passages that could have come out of current political debates) but the position of women has and the novel is interesting on both subjects.
The political situation is this: there's a crisis, a coalition government is needed and Plantagenet Palliser, who's been at loose ends ever since he became the Duke of Omnium and had to leave the lower house of Parliament where he'd really made his career. He's not terribly successful as a political leader, though he holds the Liberal Party together and gets the country beyond the coalition phase. He's not successful because he's too honest and forthright and doesn't have time, patience or guts for the game, but also because he's too thin-skinned and too anti-social. Glencora (also seeking to find her feet at the Duchess of Ominum instead of just Lady Glen) resolves to be the hostess with the mostess and to support her husband by entertaining an almost continuous string of political lights at Gatherum Castle all during the recess of Parliament. She gets her husband's agreement to spending the money so they can entertain scores of bedrooms full of guests in style at one time, but not his cooperation in sociability--he hates Gatherum Castle, crowds and small talk. There's a minor disaster when one politician inappropriately petitions the Duke who responds by ordering him to leave. Things get worse though when Glencore takes under her wing a Mr. Lopez (about whom she knows little but that he's young and charming) for the parliamentary seat at Silverbridge, traditionally under the control of the Palliser family. And she does it at exactly the time the Duke announces that he will in future keep hands off and let the Silverbridge electors elect whom they choose. Subsequently, the political rag latches on to the Duke's dishonesty in only pretending to take his hands off the political strings but secretly supporting a candidate for Silverbridge. Unlike most politicians who ignore the rag, the Duke is hurt deeply, broods at length but feels his hands are tied (remember he's fundamentally honest and decent) because he can't blame his wife for disobeying him.
The other thread of the novel focuses on Emily Warden, the daughter of a wealthy attorney, who meets that same Lopez at her relatively foolish aunt's house--and falls in love with him. Mr. Warden disapproves and tells her so but kind parent that he is (there's no mother in the picture) he eventually gives in because she insists she'll never be happy without him. Lopez, it's clear from the outset, wants a fashionable wife and her father's money, but of course Emily doesn't see that--until they are married and he enlists her help to get her father's money. Emily is quickly disillusioned but trapped. He's her husband and she must do as he says, live as he wants, etc. Even when her father promises to do everything he can to help her even if it means taking her abroad to avoid the courts which would order her back to her husband, she refuses, feeling she has disgraced herself and must pay the price. There's also an old love in the background who actually is elected member for Silverbridge.
There isn't much contact between Glencora and Emily, but it's easy to see they're in a similar situation--tied to a husband they don't agree with but powerless to act on their own. Glencora is older and wiser of course and Palliser is the exact opposite of Emily's outrageous lying husband. Though the ending is predictable, you'll still read it eagerly to see how it all plays out.