Part of being a writer means accepting rejection. Anyone who has searched for an agent or submitted manuscripts is aware of this hazardous aspect of the profession. Unless you are somehow lucky enough to become the new flavor of the month and people line up for any old scrap of words you throw at them, rejection is unavoidable. But even those on a winning spree will eventually taste the other end. When their flavor is replaced, they'll feel the sting of being told no thanks.
Publishing a book is more difficult than simply writing something that is good. It's a process of finding the right place for the story at the right time. Lately my luck in that department has been slim. I recently finished a manuscript that I know is one of the best I've ever written. Though as my agent tries to find a home for the book, it seems to be too similar to something else or not quite what we're looking for...and though those are all valid reasons that I understand, after a while it's hard not to let it get to you. You start wondering if it weren't better to just have a crowd of people line up outside your door to punch you in the stomach. At least that would be over in one day.
Though I remain hopeful, and there are still several people considering the project, it never gets easy to accept rejection. It comes with the job, but it's a part that never gets easier. All one can do is keep their fingers crossed and hope the next reply is a resounding YES.