So you're trying to make her happy despite the fact that the reason she's unhappy in the first place is you," said Simon, not very kindly. "That seems contradictory, doesn't it?" "Love is a contradiction," said Jace.
Cassandra Clare (2012). “Cassandra Clare: The Mortal Instruments Series (5 books): City of Bones; City of Ashes; City of Glass; City of Fallen Angels, City of Lost Souls”, p.1535, Simon and Schuster