You can't marry Khajits in skyrim, nor Argonians. I'm glad to be honest, the game is pretty laid back on homosixual marriages, but I'm glad they aren't as laid back on bestiality.
Actually there are 3 Argonians in the game that you can marry... 2 male and one female... And I don't think it would qualify as bestiality if you were of the same race... Problem with this logic of them not allowing it is that a Khajiit or Argonian main character can marry whomever they please provided they meet the prerequisites for marrying the particular person they choose no matter their race...
This is why I'm annoyed that there are no Khajiit in the game to marry or Bosmer... Why aren't all races represented as marriage candidates, and why the heck is the only female Altmer option freaking ugly...