In the western sky, a shooting star blazed a blood-red arc across the heavens, sending the numerous couples beneath who held spectacle to its descent into bouts of enthusiastic prayer and wish-making.
Those couples expected the star would fall?
In a descriptive sense, the star did fall—across the sky.
It's a somewhat uncommon expression, but to say that they held spectacle to its descent means that they observed the spectacle of its descent.
Typically, shooting stars are associated with blessings and well-wishes.
A variation of this (one that is more transitive) would be something like:
She was in awe at what she was held spectacle to.
Of course, it need not be positive:
She was aghast at the horror of what she was held spectacle to.
From Merriam-Webster's definition of spectacle:
1 a : something exhibited to view as unusual, notable, or entertaining
especially : an eye-catching or dramatic public display
You've missed out the important context:
The Qixi Festival happened on a summer night. In the western sky, a shooting star blazed a blood-red arc across the heavens,...
The Qixi festival is an annual event in China in which young couples go out to look at the stars, as it celebrates two lovers who were separated, and became immortalised as the stars Vega and Altair, on either side of the milky way. It is a day when girls make ardent prayers to find a lover and couples hope that they will have a happy life together. This is why there were numerous couples looking at the stars. The appearance of a shooting star would be a good time to make your wishes and prayers.
It just means "see the scene".
You have asked if it means "expected". I think you just confused spectacle and speculate, and thought they expected a star falling.