"-Because I love you."
Her face, so sincere and determined, made him want to love her. She was the only girl to ever tell him she loved him and he'd give anything to return the feeling.
But, Naruto will be Naruto, and his second thought was:
I wonder if she'll let me touch her boobies...
You know he was thinking it. And who wouldn't? Hinata has such big boobies. DON'T LIE! I know you've thought about it! Like, I wonder if she got a boob job?
Naruto is just 15, horomones and all. :D