Our story wasn’t over

I met him 17 years ago at the beach, when we were both 17. It was love at first sight, but that week ended way too fast.
Four years later, I took a chance to drive 3 states away to see him.
It was a whirlwind romance that lasted two years. But we were young and the distance got the best of us.
We kept in touch, married other people, started families. But part of me always wondered about someday.
Last week, he died. And I am shattered.
Our story wasn’t over, but now we will never get the chance to finish it.
How do I grieve someone I am not supposed to love?