She would be heartbroken. Sakura has known Naruto for a long time, and his death would shatter her world. She may become more withdrawn and serious. In the long run, she could use her pain as motivation to become stronger. Maybe she would train harder than ever before to make sure that no one else has to suffer the way Naruto did. She might also start to see Naruto in a different light, realizing all the things she took for granted when he was alive.
She might be surprised at first. After all, Naruto isn't known for his singing usually. But then she could be touched if she realizes the song is for her and about their relationship, whether it's friendship or something more.
She would also be deeply emotional. Sakura has deep feelings for Naruto, even if they were not always fully realized or expressed. His sacrifice would make her confront these feelings head - on. She could be seen crying often, visiting Naruto's memorial frequently, and having long internal monologues about their relationship and what his sacrifice means to her.
Sakura might be completely shocked at first. She might freeze for a moment, not believing what's happening. Then she could start crying tears of joy and say yes immediately.
Sakura may react with a sense of urgency. She would drop whatever she was doing and rush to Naruto's side. She'd be worried that something truly terrible has happened. If Naruto is hesitant to talk, Sakura might just sit quietly with him, waiting for him to open up. This would show her patience and understanding, and also how much she values Naruto as a friend.
Sakura would be devastated. She would probably blame herself for Naruto's death since he died protecting her. She might go into a state of deep depression at first, withdrawing from everyone.
She might be initially shocked and hurt. Sakura has always had Naruto as a constant in her life, so his sudden absence would be difficult to accept. She could become withdrawn and start to question her self - worth.
Sakura would probably be horrified. She knows Orochimaru's reputation for being cruel and power - hungry. She would immediately reject any offer from him and get ready to fight if necessary. After all, she has grown into a strong kunoichi and won't be easily intimidated.
Sakura might initially be terrified. She would probably try to fight back using her combat skills and medical ninjutsu to defend herself. Since she is a strong - willed character, she won't go down without a fight.
She might be confused at first. Sakura is used to Naruto being friendly and always there for her, so his coldness would be unexpected. She may start to question what she has done wrong.
Naruto might also try to remember Sakura in a positive way. He would cherish the memories they had together. He could start initiatives in the village in her name, like promoting medical ninja training more, since Sakura was a great medical ninja. He would slowly turn his grief into a force for good in the village.