
People keep on expecting Sakura to fangirl on Sasuke but she isn't at all it's all Hinata fangirling on Naruto.
Karin saw Sakura's sadness. Karin would feel confused, but being as she is an Uzumaki, Karin will take the first oportunity and take Sasuke for her. Sakura doesn't seem to consider Sasuke romantically anymore.