I'll admit it. I like endings with all the loose ends tied up and all the good people, if not happy, at least content. I have a hard time really hurting my characters, and when I read, I dislike it when the author dwells too long on torture or even mental anguish, especially of an innocent.
It's not a bad thing, but I have to watch the Pollyanna stuff. It's hard to create tension in a story when everyone is nice to everyone else, and even good guys have to be irritating at times to seem real. One way to counter overly nice characters is to list, before you begin writing, both good and not-so-good traits for your characters. So Mary is the protagonist, and she's going to prevail in the end. She can still be a tiny bit odd: anal retentive, maybe, or prone to fits of paranoia. A lot of authors like a hero who can't commit to a relationship, which gives them a flaw and also bodes well for sequels. Stubbornness is also good: the cops can tell your hero twelve different ways not to interfere, but personality trumps authority every time.
On the other side of the coin is the danger of a character becoming too irritating. This is especially true in series, where traits continue from book to book. I won't name names here, but who hasn't quit reading a series because the protagonist's demons have become too much to take? We find ourselves wanting to shake him/her and say, "Get a grip!"
It's a balancing act, then. Characters have to be a blend of human strengths and weaknesses to appeal to readers, but we must remember that in a novel (unlike real life), the reader can close the book and refuse to deal with a person who comes across as either too offensive or too perfect. I contend that it isn't bad to reward the good guys and gals at the end. Most readers like the happily ever after part, as long as the story leads them to believe in that happiness.