This hurts. Among my favorite trad Regencies are a couple titles by Dorothy Mack: The Awakening Heart and The Unlikely Chaperone, both dry-witted tales with a rare and appealing willingness to let the heroine look ridiculous at times.
So when I found The Steadfast Heart at a used-book sale (someone was unloading her entire collection of Signets, it looked like, which made me a bit melancholy), I snatched it up. The h/h appear as the Established Couple in The Awakening Heart, so I looked forward to learning their own story.
But the going was kind of slow. Hero disapproves of heroine's candor and spontaneity, blah blah; misunderstanding; appearance of indiscretion; marriage of convenience; agreement to postpone intimate relations. And then the hero goes from irritating to monstrous. He suspects her of having an affair with his cousin (hero of The Awakening Heart! Dude, you leave Charles alone!) and says and does some things that are point-of-no-return unforgivable on my Hero Behavior Scale. Insults her with the infidelity accusation to the point where she threatens to get an annulment, and then breaks the postponed-intimate-relations agreement to make annulment impossible (legally not rape, as they're married, but pretty damned unpleasant nonetheless).
Incredibly, they patch things up and eventually have enjoyable sex. But he goes off to the Continent for some military reason, and when she shows up there a couple months later, pregnant but not as big-bellied as you'd expect a woman that pregnant to be, he assumes the child was conceived in his absence and accuses her of whoredom all over again.
That's when I quit. The guy has clearly demonstrated his nature. If she stays with him expecting him to change, she's a fool.