What I gathered from Origins was that Anora was fond of Cailan - after all, she is definitely unhappy with the fact that her father sort of threw him away because he was in the wrong place. True love and respect... hmmm, those are rare in an arranged marriage. Fondness was probably the best she could hope for, and he isn't that ugly.
And it's painfully logical for Eamon to say it's the wife who's infertile.... throughout history, nobles have a serious tendency to do this. Must be because, while there should be heirs, you reply to your king: sorry you can't get it up, dude.
Although, Cailan probably wouldn't have minded. Or maybe he'd cry