This also means that I just finished my session in which I taught about including romance in novels! And I'm going to give you an overview right here.
First off, romance is vastly important in storytelling. I don't even WANT to have to argue this again. It just matters. Love makes the world go round, is all you need, etc. Character relationships of all kinds are founded in some shade of love, and they're necessary to character development, plot structure, and most of all, emotional impact. Friendships, family, you need positive interaction to reveal all the depths of your story. It's what readers connect to most! Romantic relationships are just another form of this, as well as a powerful, key part of human existence. I doubt the existence of many books/movies/TV shows that don't portray romance of any kind, even if it's only background romance between side characters (even between the main character's parents!).