Marriage is a relationship by another name. One that is more socially-binding, so far as personal perspective and those of others and of society, but at the end of the day it doesn't change the fact it's another word for a relationship.
I found this quote and liked it:
"Books loved anyone who opened them, they gave you security and friendship and didn’t ask anything in return; they never went away, never, not even when you treated them badly."
— Cornelia Funke, The Inkheart Trilogy