Unresolved grief/loss

I wonder how messed-up I am that I'm still not over my first love.

Just to clarify, though... when I'm dating someone else, I'm 100% committed to the other person.  There isn't even the slightest bit of emotional cheating, whatsoever.

It's just that when the break-up happens, I start to grieve simultaneously and the pain of my 1st breakup will roar back with full force.  That's definitely some unresolved issues there.

Is that normal? Or does that just happen to me?