My friend. At this point, I doubt it can be taken back XD. Wikipedia says "Asami Sato...Korra's Girlfriend" right the first on the list. And to be honest, I dont look into my friends eyes the way Azami and korra looked at each other at the end. So yes. It is, and nobody can take it away, canon. Enjoy.

*offers cake* here, let's eat cake.