I took these words from the CofE wedding service; dh and I said them to each other 10 years ago and they have held us together through all the highs, lows, travelling, career-building, babies, deaths and general minutae of everyday life together:
"I, Sarah, take you, John,
to be my husband,
to have and to hold
from this day forward;
for better, for worse,
for richer, for poorer,
in sickness and in health,
to love and to cherish,
till death us do part,
according to God's holy law;
In the presence of God I make this vow"
With my body I honour you, all that I am I give to you, and all that I have I share with you, within the love of God, Father, Son, and Holy Spirit."
To me that really is the heart of it; it's about deep ,abiding trust and looking after each other, come what may. I'm not daft; I know that not all marriages do stay together "till death do us part", but I believe that if you've made a solemn vow in public like that and genuiunely meant to do your utmost to live out the words of the vows, you can't have a better foundation for a life together.
But of course I would say that, (I'm hoping to train as a vicar).