I think it requires full-on, no-doubts, no-mind-changing commitment and, yes, love, but not the way "love" can be typically portrayed.
Loving someone is an action, not just an emotion. I may not like my husband all that much, feel angry or disappointed at him sometimes, but I can still choose to do my best to love him.
Plus, of course, a certain amount of compatibility definitely goes a long way- not only in the sense of doing/enjoying the same things, but also in the way that one person's character strengths and weaknesses can complement the other's.
That's my take. (: