So, I'm watching Dawson's Creek, which is a drama full of, well, drama. Anyhow, one of the characters is writing a love story, and an ex-girlfriend of his offers him the advice not to give it a happy ending, because they're unrealistic. Now, this is largely supposed to be a highly cynical comment (the person saying it is drunk towards the end of a spiral out of control). Yet it actually contains a rather insightful metaphysical point, though it's in the words that the person said, rather than in the meaning that she had for them.
There are no happy endings, there are only happy middles.
Happiness comes from something real, something that is, something that has being. Endings are a transition from existence to nothing; when the end is over, there is nothing. (In the physical world in which we live, there are no complete endings; all endings are also beginnings. In the spiritual world there are, presumable, complete endings.) And nothing can never bring happiness.
Discussions of movies always muddy this, because the movie's ending is (if you take the fictional reality seriously) not an end to the events in the movie, but only an end to the viewer's glimpse into it. Movie endings are almost universally ambiguous: "And they lived happily ever after" doesn't mean that the characters were henceforth immortal. In most cases it means that nothing very remarkable happened to them. They did at some point die, and few deaths are completely without suffering. What "happily ever after" means is that the characters never again had the same sort of troubles that made them interesting to us. It doesn't mean that they were free from all human cares.