I wasn't going to weigh-in on this since the OP seemed to be asking specifically about christian viewpoints, but that hasn't stopped anyone else ...so here goes!!!
Devotion, in my eyes, is one of the most beautiful human emotions because of the things it makes a person capable of doing. It can make a captain in down with his ship to save his crew. It can make a fireman run into a burning building to rescue a total stranger. It can make a samurai slice open his belly and bleed out on the floor so his master can save face. I fell in love with the idea of having that in my life. Devotion to someone, something, a cause, a purpose, an idea...something that could become so important, such a part of who you are that you would not want to live without it, because without it you would not be the same. It made you more than what you were, and without it you'd be less. I spent long years hoping I'd find that in my life...and not finding it. The idea faded until it was all but forgotten when I met my wife.
It sounds corny to say something like "love at first sight" because before I saw her I didn't believe in it. I don't know that I do now, but I was certainly smitten with her. She has a rare, almost exotic, beauty that's natural to her...something effortless. I've told her she falls out of bed beautiful, and she's stunning by almost any man's standards. Nothing unusual about me desiring her, what red-blooded man wouldn't? However, it didn't take more than a couple conversations to realize she was so much more. He's beauty inside makes her physical beauty pale in comparison. I've known only a handful of genuinely good people in my life. Most people I regarded as capable of good, but few were good as a part of their nature. She stood above even them, like some angelic being flowing with grace. So genuinely kind, loving, compassionate, affectionate, understanding...from her such things are infectious. It was as if I'd found this amazing girl who was somehow unspoiled by the world. Untouched by anger, jealousy, wickedness, cruelty. When I learned how wrong I was about that, she just became more wondrous. Such sad and awful things had been a part of her life for so long and yet she was still practically a saint in my eyes. She's stronger than I am in that way.
I could go on for days but I'll spare you. Suffice to say, I wanted to be the kind of man who deserved her, the kind of man she deserved, the kind of man I wasn't. I changed everything about my life to be worthy of the love she gives to me so freely. I wanted to be able to have her always, she already had me completely, anything of me she needed only ask. She became the thing in my life that I am entirely devoted to. Her happiness is my greatest cause. Her love is my greatest pursuit. Her trust is my greatest treasure.
Our marriage is just a symbol of our commitment to each other. I don't know what a spiritual marriage is and if I did I doubt I'd have any use for it. I don't know any gods, but if I did I wouldn't bother with anything so trifling as a commitment to/before them. My marriage is a symbol of my commitment to her. A symbol of our devotion, our trust, our love. It is the only thing in my life I consider sacred, she is the only thing in my life worth dying for.