Fabian didn't really know why he was parading the streets of Hogsmeade with a girl that was not Hestia on his arm.
He also didn't really know why he was thinking about such things as swapping his date for his best friend.
He also didn't really know why he was crazy-jealous of the smug berk Hestia was accompanying.
It had all started this morning, when he met Bonnie at the courtyard's entrance. She had straightened her hair – her long, blonde hair. (It was then that he decided he preferred black hair – short, curly, black hair.)
She had fluttered her eyelashes – mascara coated things, hiding dusty brown eyes. (It was then he decided he preferred thick, dark mascara-less eyelashes, that hid electric blue irises.)
She had waved off the fact he was a few minutes late and laughed at his jokes. (He wished she would snap and ignore and get mad at him for being late, and moan about how damn awful the jokes were.)
In short, she was probably Hestia's polar opposite. (He was ashamed to admit he preferred Hestia's end.)
But he couldn't exactly say anything, for he was much too much of a gentleman (or just not a complete dick) as to admit he would rather be here with Hestia Jones than her.
Also, he couldn't exactly say anything to Hestia, for he didn't know why he wanted her here instead of Bonnie, and wanted to hex Matthew Donohue into the next life.
All in all, Fabian didn't really know what was going on, or why he was feeling so strange in regard to his best friend of four and a bit years.
So, nothing new.