Haru:

"There are plenty of fish in the sea...A lot of them are free, but this one is not. (-3-)"

Makoto:

"If I had a penny for everytime I thought of you, I'd have one penny because you never stay off my mind."

Nagisa:

"You're so sweet; you're gonna give me diabetes!"

Rei:

"Roses are red,
Violets are blue,
I didn't know what beautiful was
Until I met you."

Rin:

"I can show you a sight you've never seen before."

Momo:

*Can't think of one for him ;-;*

Kisume:

"You can kiss uh me.~"

Nitori:

"Notice me, senpai." XD

Sousuke:

"Out of all the stars in the sky, you're the star that shines the brightest."

Most of these I looked up XD I just chose which ones would suit them best :3