The thing about the "unknown" is that it will ALWAYS be there. That is something you cannot control.
Your best defense is a good offense.
In sports, in marriage, in life.
Compromise, and compatibility, not perfection.
You must be best friends first before you can ever hope to make it in the long term sense. Soul mates come in all shapes, sizes, and they do not even have to be human: they could be your childhood pet, your favorite painting, a book that changed your life forever.
Life is in the details.