Pretty self-explanatory.
Mine: You’re Still the One.
My husband and I have been married for 5 years, but excluding a breakup 6 years ago we’ve been together 14 years now. When we decided to get back together and get married there was more than one person that doubted we would get through the year. 5 years, and still going strong. 
So…what is your song?
Okay, this is definitely corny, but if you’re old enough, you may remember Donna Fargo, and her song “Happiest Girl in the Whole USA”…
Hey, I said it was corny. But we just celebrated our 14th wedding anniversary and we’re happier than we’ve ever been. 
“Be My Life’s Companion,” as recorded by the Mills Brothers.
“Happy Together,” the Turtles. 
Well, lately it’s been John Cage’s 4:33 .
Well, unless it’s obvious, a little explanation on why you chose your song would be nice.
Well everyone has to feel like this from time to time.
(Click for cute running-bunny animation/song)
When I said I Do by Clint Black. That and Jimmy Buffett’s Why Don’t We Get Drunk (and Screw)? 
Sorry, I just mean I haven’t been getting any.
“Love the One You’re With”* would prob’ly cover it these days. 
It’s a bit cliche, but all in all a great theme song for a married poly chick. I find it a leeeeetle offensive in its assumption that you can/should only “love the one you’re with” when “you’re down and confused” because “your baby is so far away”, but one really mustn’t read into these things too deeply.
The song that’s always best described my relationship with my husband (and, hence, it’s “our song”) is “Goodbye Sweet Pumpkinhead” by the artist formerly known as Jane Siberry. Alas, the link to the left of the lyrics does not, in fact, lead to an audio file of that song, but her better known “Calling All Angels”. I recommend seeking out “…Pumpkinhead”; it’s a really sweet and interesting song. My husband and I put in on each other’s first mix tapes, when he was leaving for the UK for four months.
*Sorry about that hideous background, but it was the only page I could find that didn’t consistently misspell “you’re”. :smack:
ETA:
I thought your response was brilliant, actually. 
What I Like About You by The Romantics.
I got that, it was the one before you I didn’t.
Beautiful by H.I.M. http://www.youtube.com/watch?v=wStG1xBSIHs
These Days, performed by Tom Rush. I think it’s a Jackson Browne song and I think the Nitty Gritty Dirt Band also did it. But I like the Tom Rush version. Anyway, the whole thing sort of rings true for me, especially these lines:I had a lover,
I don’t think I’ll risk another, these days
and the ending:Don’t confront me with my failures,
I have not fogotten them.
“Imaginary Lover”!
“Have you heard about the lonesome loser, beaten by the Queen of Hearts every time . . .”
You didn’t get “Happy Together?” 
But it ain’t me, babe. No, no, no, it ain’t me, babe…It ain’t me you’re lookin’ for, babe.
I’m enjoying being single 
Just needed a bit of context.
I am nosy like that.
Right now I’d have to say Tir Na Nog by Van Morrison
…because I recognized her chin 7 years ago and she kissed mine eyes.