I actually hope people don't react to 'Impossible' in a way where they think it's terribly retro. The plot needed to do what it needed to do. But I'm a little surprised to find myself looking a little bit like an advocate of teen marriage. It takes some exceptional circumstances for that to be a reasonable idea.
I used to want covers that represented the book's contents very closely and were also pretty. Many folks automatically believe that this is what makes a good cover. But I've changed my mind about this. While the cover should not lie (by implication or outright), its job is simply to say: 'Pick me up!' to someone who might like the book.
No matter how beautiful and loved a cover may be, the jury on it remains uncommitted until the book has been in the world for a while. Perhaps bookstore buyers will be indifferent. Perhaps it will be lost on store shelves. Perhaps there's another book or two out there using the same or a similar photo.