I Don’t Understand

I understand 

"head over heels"

it means

"you keep me sane"

"you're my reason for living"

"without you,

I'd lose my head"

I understand

"madly in love"

it means

"I'm crazy over you"

"I'd do anything for you"

"I love you so much,

I'm going insane"

I don't understand

"falling in love"

Because with you,

I'm flying.