Writing for the new algorithm

I just had a successful launch of Born of This Fire (aka BOTF) in which my Civil War novel of love, marriage, and family saga never ranked for the most applicable category, historical romance. This is also a genre that has huge competition among big-name authors.

Now that I've studied the new Amazon algorithm, I understand that putting love and marriage in the keywords, categories, and even in book description is not enough. It has to be in the actual book manuscript because Amazon looks for keywords there, too. Love and marriage are definitely the theme of BOTF, but the theme is not clearly stated in those words.

So I'm wondering: If I went in and sprinkled the keywords love and marriage throughout the novel itself, then redid the back cover copy and categories, might it be shown to more readers of romance or at least family sagas? Is there something wrong with doing that, or would it truly serve my readers?

 I look forward to your reactions!