Of course, it wasn't a true marriage, just a mutually agreed-upon political agreement. You're the Dragonborn, you fought by his side in the war, there was a mutual respect between you, but nothing more. Yet you were surprised by his proposal: that he propose to you. Even if you don't fully understand his intentions, you want peace in Skyrim, so you accepted, even though this man is old enough to be your father and you certainly know his contempt for non-Norse species. This realization left you speechless, even after the wedding, as you walk beside him toward his chambers in the Hall of Kings, you're still perplexed.