Four authors, one story

This anthology contains four regency romance novellas by four writers: Stephanie Laurens, Mary Balogh, Jacquie D’Alessandro, and Candice Hern. All four tell similar stories.
The hero is a younger son of an aristocrat and a former officer. The Napoleonic wars are over, and our hero is retired from the army. He stays away from society to heal his physical and mental injuries, until his older brother, the heir to the title, drags him out of his seclusion. The problem is, the older brother could only father several daughters. Concerned about the title going to an obnoxious cousin, he calls upon his younger brother to do his duty: to get married and produce a male heir.
The heroine in all four stories is a woman a few years older than a school girl. For various reasons, she is considered unsuitable: for our hero or for anyone else. In all four tales, she is sure she will never get married. She is either a commoner art teacher, or a crippled girl, or a shy widow who disliked her first husband.
Their first meeting doesn’t inspire love at first sight. After all, the hero is marrying under duress. Then the hero and heroine engage in a mating dance, with a spattering of danger and mayhem, and after a while, the rules of the genre take over the story, and the inevitable L word blooms on the last pages of each novella.
I like romances, and I liked these four, although some of them were better than others. Nothing spectacular but nice and readable.