The following article contains an answer for the question: What is Terry's condition that goes unnoticed by Nickie when he sees her at the ballet? , can you please find it? 

Nickie Ferrante, a well-known playboy, meets Terry McKay aboard the transatlantic ocean liner SS Constitution en route from Europe to New York. Each is involved with someone else. After a series of meetings aboard the ship, they establish a friendship. When Terry joins Nickie on a brief visit to his grandmother Janou while the ship is anchored near her home at Villefranche-sur-Mer on the Mediterranean coast, she sees Nickie with new eyes and their feelings become deeper. During their visit, Janou tells Terry that Nickie is a talented painter but destroys most of his paintings because they don't meet his standards. As the ship returns to New York City, they agree to reunite at the top of the Empire State Building in six months' time if they have succeeded in ending their relationships and starting new careers.
On the day of their rendezvous, Terry, hurrying to reach the Empire State Building, is struck down by a car while crossing a street. Gravely injured, she is rushed to the hospital. Meanwhile, Nickie, waiting for her at the observation deck at the top of the building, is unaware of the accident and, after many hours, leaves at midnight, believing she has rejected him.
After the accident, Terry, now unable to walk, refuses to contact Nickie because of her disability. Instead, she finds work as a music teacher. Nickie has pursued his painting and has his work displayed by Courbet, an art shop owner. Six months after the accident, Terry sees Nickie with his former fiancée at the ballet, which she herself is attending with her former boyfriend. Nickie does not notice her condition because she is seated, and she says hello as he passes her.

unable to walk