I believe it was police novelist Joseph Wambaugh who noted that when prostitutes leave the business, about the only suitable mate for them are policemen, because there are no illusions in either case.
Instead, theirs is a relationship of mutual understanding and some degree of sadness. The feeling that to some extent they are both emotionally damaged goods, that they both have experienced things which had harmed their souls, and that what redemption that may find begins with kindness, gentleness and healing.