For me, the relationship is always the most important, whatever form it may be.
However I will say that I've reached a point in my life where I'm highly unlikely to begin a relationship with someone who isn't either actively poly or very familiar and comfortable with the concept.
A few too many experiences with those who had never heard of the word, said "Oh, yeah, that sounds great!" but down the road (after of course, the love had grown deeply) it turned out not to be something they really could live with and I've rather sworn off non-poly folks in general.
I've also been around long enough to know "never say never" though.
Love often shows up in the unlikeliest of places.