Wicked Lovely

Wicked Lovely by Melissa Marr is about a girl with the Sight. She has lived her life by three rules:

Rule #3: Don't stare at invisible faeries.

Rule #2: Don't speak to invisible faeries.

Rule #1: Don't ever attract their attention.

And it has worked. Until she met Keenan, the king of the Summer court, and he is determined that she will be his queen. As Aislinn breaks all the rules and is drawn, inexplicably, into faerie, she discovers friends and enemies she never knew existed! 
Really good book, reading it for the second time at the moment!