Let's talk a bit more about the appearance of your finished product.

Keep your summary short but interesting. The summary should match the tone of your book. If it's a light and fluffy romance, you want your cover and summary to reflect that. If it's a horror book, you aren't going to have puppies frolicking happily across your cover and your summary won't begin with something light-hearted. 

For example, if your summary begins with something dark, like your character's tragic past, then it's likely that the tragic past plays a big part in the book. Perhaps as the book progresses, the character falls in love and the theme becomes lighter, but that doesn't erase the tragedy. Things stick with people, and it can affect how they live their lives in the present and how they react to things. An abusive past can leave a person with a lot of issues that affect how they react to those around them. From success and failure. They will struggle with it for the rest of their lives in some capacity. Falling in love doesn't cancel out the tragedy. You need to remember that when writing the story, creating your cover, and writing the summary. Everything needs to revolve around your central theme, the genre, and the overall mood of your story. 

Everything needs to go together logically and seamlessly.