A History Nut's Romantic State of Mind

I am usually rather forgiving when it comes to these old bodice ripper books. I know it was a different time and generation. This was hot then and somehow not unrealistic. So when I say I did not like this book, it is not because the book was politically incorrect, or how the heroin suffered or what a jerk the hero was. I read somewhere that this was Mason's first book. I have to say, Johanna Lindsey's first book, Captive Bride, was also politically incorrect, but it was better than this book.
This book suffers from the same problem as Lindsey's Captive Bride: it just is not written very well. The chemistry is all off, the characters act unreasonably, and THERE IS NO PLOT except for SUPPOSEDLY great sex.
The story started out alright, a convent raised girl was sold to a plantation owner for her father's debts. Her husband cannot have enough sex with her. She resisted but then gave in to the pleasures. Then she was so beautiful every man who sees her wants to sleep with her. So she did with a gentle man who said he loved her, when she was separated from her husband in an accident. Then the guy had to go away and she hid with another guy while refusing to go back to her husband all the time, only to be found by her husband later. Her cruel husband who she left behind and cheated on, turned into a loving angel proclaiming care and devotion when he found her again. Her husband begged her to come back knowing that she had taken a lover and was waiting for him to return.
And this is as far as I got with this train wreck of a book. It is not the cheating that bothers me. I know some readers hate it but I have to say such is life and people suffer. Cheating is not something great but sometimes it happens out of desparation. But what I can't understand is how the hero turned into a loving bear after she cheated? I mean come on! I get that you have to turn lust into love in a romance story. It's a must. But do it with some tact please. It has to be believable. You have to convince me as a reader that yeah they somehow managed to let down their guards.
I think it's enough to say that this book's worst part is being written very poorly. The plots and circumstances don't bother me. The political incorrectness doesn't bother me. A book's biggest crime is being a poorly written book. And Tender Fury is a capital offense.