I’m not sure if Tolkien would fully agree (we’ll find out when we get to glory) but if ever I have a pre-marriage counselling room, the verse I want hanging all around the walls is the comment by Gimli, moments before he (and Company) depart Rivendell:
Faithless is he that says farewell when the road darkens
These words come in respond to Elrond having given the Company (bar Frodo) permission to abandon the quest if at any point they feel unable to continue:
You may tarry, or come back, or turn aside into other paths, as chance allows. The further you go, the less easy it will be to withdraw; yet no oath or bond is laid on you to go further than you will. For you do not yet know the strength of your hearts, and you cannot foresee what each may meet upon the road.
To this Gimli responds with that challenging yet profoundly biblical line: Faithless is he who says farewell when the road darkens. Isn’t that precisely what the Christian marriage wedding vows get at with it's sobering:
For better, for worse
For richer, for poorer
In sickness and in health
To love and cherish
TILL DEATH DO US PART
May God by His grace enable us to stay faithful to Him and each other to the very end. Amen.