I'm getting married and most of our friends and family don't know
Why do you want to marry this person?
I love this person. I'll be happy with her until I die.
Marriage is between two people but the people you know would want to be a part of it. It will hurt their feelings if they didn't get to share in this occasion.
Okay, I'll tell them. They can figure it out for themselves how to make it to the wedding.
I am glad that you decided to let them know but you should let them know with enough time so they can make it. Family and friends expect to be there for you in your important events.