Why does she say Na Na Na Na?

[i][c=#7700B2]
Na Na Na Na…

Na Na Na Na…

Separating myself from the world
I will embrace You and keep You by my side
I Wanna Say You
I will always be by Your side

After talking all about my love for You

I’m dying now by falling in love with You
I Wanna Say You
I will always be by Your side

Because...

I am Your boyfriend, I am Your boyfriend
I am Your boyfriend, You are my girlfriend
Why does she say Na Na Na Na? [/c][/i]😏