She knew he was too mad

Marylou was watching Dean as she had watched him clear across the country and back, out of the corner of her eye - with a sullen, sad air, as though she wanted to cut off his head and hide it in her closet, an envious and rueful love of him so amazingly all himself, all raging and sniffy and crazy-wayed, a smile of tender dotage but also sinister envy that frightened me about her, a love she knew would never bear fruit because when she looked at his hangjawed bony face with its male self-containment and absentmindedness she knew he was too mad. Dean was convinced Marylou was a pathological liar. But when she watched him like this it was love too; and when Dean noticed he always turned with his big false flirtatious smile, with the eyelashes fluttering and the teeth pearly white, while a moment ago he was only dreaming in his eternity. Then Marylou and I both laughed - and Dean gave no sign of discomfiture, just a goofy glad grin that said to us, Ain't we gettin our kicks anyway? And that was it.

Jack Kerouac – On The Road, 155