Anyone reading the Elm Creek Quilt novels?

Maybe someone who’s read these can help me. I’ve read all these frickin’ books, and I really like them for light reading, but I’m having trouble remembering all the characters and plots from one book to the next, especially when they go back and forth from the historical ones to the present-day ones. So, I’m reading the latest release, The Union Quilters, and it’s taking place during the Civil War. I’m going to talk about it in broad terms, so I won’t spoil anyone if they haven’t read it yet.

Basically, it’s involving all the people in Water’s Ford, PA, who were characters in The Runaway Quilt, and I think maybe one other book that involved the Underground Railroad? Anyway, one of the characters, Gerda, is in love with a doctor named Jonathan, and he’s in love with Gerda, too, but he’s married to a lady named Charlotte. There’s obviously some backstory as to how he ended up married to Charlotte when he and Gerda are in love with each other, but I don’t remember how it happened. Can anyone remind me, because it seems kind of crazy, and there must be some plausible explanation?