Author's Note: Slight spoilers for "Need to Know." Also, it will not make any sense if you haven't seen that episode. As it is a very short drabble about one moment in the episode.
Fantasies, by your definition, do not come true.
You did not fantasize about graduating from medical school at the top of your class, or getting a top fellowship. You did those things, you accomplished them.
You fantasized about these things: about Sam Taylor asking you to the prom when you were a freshman, before you had breasts; about your humanities professor, freshman year, who leaned back in his chair and nodded when you talked. You fantasized about Michael getting better, suddenly, walking out of the hospital holding your hand light and sure. You fantasized about the baby you killed, without telling him, the baby that never was, and about Joe, shamefully, listening to the beep of Michael's heart, Joe's mouth on your stomach where there were no scars, his lips on your pelvis, his hands. (You didn't fantasize about the funeral, you never thought of it, it came and left while you were not paying attention.) You fantasized about quitting medicine and becoming a housewife, laying around all day reading novels and eating chocolates from a box. You fantasized about all the things that could not be, that would not be.
So when House stopped you, out of the blue (of his eyes) and said, "I love you," you thought, I know I am awake, I know this is real, and your whole understanding of fantasy changed, for a second. Just that. Because awake doesn't mean real, a false conflation of terms. Because everyone lies.