That's someone he knew in his childhood and probably has a strong platonic image of. Marrying her makes sense for him if he was in love with her.
I don't see that marriage being a happy one though. After he tells her about the exotic kingdoms and kings he met, the monster his slew, and she mentions that two years ago, a horse fell in a well...Well, She can't offer him much, can she?
And you honestly think her body gonna hold a candle to the battleforged muscles of an Amazon girl, or the lithe, agility build of his ex-party's rogue?
He gonna be banging her and dreaming of the blond hair and creamy skin of the Paladin Chick he spend two years of his life travelling the wilderness with. While this chick did the same boring ass thing for 10 years.
The true drama of an adventurer is that...Nobody understand the world as you do, unless they are another adventurer. And those are rare, few and far apart. You saved the world, but you don't belong in it. You give your blood and sweat and years of your life to protect something you'll never be a part of. Not for yourself, but for those who are a part of it. You will have their love, their gratitude, their admiration...You'll inspire kids to try and follow your step. But you are just not made of the same thing as they are.
You saw the Abyss, demons, dragons, other dimensions. King's, Emperor, Sorcereress. They never went further than ten miles from where they were born. But the worse? They never needed to. They don't have that cursed wanderlust that made you into the superhuman savior you are.
Damn, I'd kill for a GM that could capture that well enough.