Jivara (female Avatar) married Chrom in my first playthrough while Andiro (male) married Lucina.
I had her initially marry Chrom to see if having the two main characters each other would affect the story in any way. Needless to say, I'm rather glad of the outcome. :) While Chrom himself is kind of low on my list of favorite characters, I've come to like the guy a fair bit. He can be kind of dense and a dork sometimes, but he means well and can be surprisingly sweet. Morgan is always a sweetheart, and Lucina is an awesome Iron Woobie of a daughter.
As for marrying Lucina, their S support is sweet, yes. I, however, don't feel anywhere near as attached to her as her husband in comparison to being her mother. I totally admit to heavy bias, both for being her mother first and for actually being a woman and thus connecting more with the female Avatar despite not considering said character to be "me."
Gangrel once, Walhart once, Chrom once. Going with Yarne this time but I haven't recruited him yet. Not giving reasons because I don't actually love any of them and only get married for completion's sake.
My MaMU marriages don't count.
Official Bride and Wife of Noire (of the Fire Emblem Awakening message board)
Oh, come on people. Fawn over your waifus a little more. Tell me why you picked them!
In my case, it was basically a 3-way competition between Cordelia, Tharja, and Maribelle. In the end, however, Maribelle's healing duties meant she couldn't spend as much time with me and Tharja joined a little too late to stand a better-than-decent chance. Meanwhile, Cordelia's speed and my strength (I picked Strength as my asset) were a powerful combination that Gangrel's army couldn't stand up against for long (we got married before Chapter 11 started - or maybe it was just engaged; I'm not sure any "married" couples actually tie the knot until the war with Gangrel ends).
Furthermore, I liked Cordelia's earnest desire to push herself as much as she possibly could, and she's also beautiful.
Plus, Chrom isn't even an afterthought for her now that she's with me!