Why did everyone get silent when pony asked soda is he would take sandy to the party?

Everyone fell silent when Ponyboy asked Soda if he would take Sandy to the party because the question brought up sensitive emotions and unspoken tensions among the group. Soda's relationship with Sandy was a source of concern, especially since she had recently moved away, and the mention of her stirred feelings of loss and longing. The silence reflected the group's uncomfortableness with discussing personal matters and the acknowledgment of Soda's heartache.