Soulmate
I'm feeling vindicated after reading this article featuring an interview with Katee Sackhoff -- the actress who plays fighter pilot Starbuck in the television series Battlestar Galactica. Leoben would be my choice for Kara's true love, too... after all, they say a soulmate isn't the person who you end up enjoying a life-long starry-eyed romance with, but the individual who understands that deepest, darkest thread of you and uses this insight to empower and encourage you to evolve into your highest potential. Out of the three, I'd say without hesitation, that Leoben understands her the most, and because they are born from the same breath, (so to speak), the understanding is reciprocated by her -- try as she might to doubt it.