The End is a long way from home

What is the perfect end? Specially when reading a book or a short story, I'm constantly dissatisfied with the final unraveling. I like fiction, but a great story is often ruined by its ending.

When a couple finally marries after a lifetime of fighting, what makes the reader trust these two will end up together? Most endings are incomplete until you do something so drastic, it's irreversible. Dying is a good example. You can't take that back.

What I'm saying is that "the end" is never final. There is always an open door to continue a story. Most of all, when the sense of closure comes entirely from trust in character.
Am I being pessimistic? No. Couples that break up on and on again are like that. The ending loses its meaning.
I like ironic ends because they reflect more closely the nature of real life. The unexpected car crash that makes a regular kiss, the last kiss. But I'm not advocating for tragedy either. Tragedies and love stories are too predictable.

I can recall one real endings in my life:
-Pamela and I had a great relationship years ago, entirely sex-driven. One day I lost my phone device and had to change my phone number. I never heard from her again. We both ignore on that last dinner, that it was going to be our last night together. I'm sure she is happy somewhere.

I'm sure there are more endings to be told, but at the time, I'm too oblivious/optimistic to recognize them.