Aerith loves Zack. Cloud loves Tifa.
No she doesn't. for (almost) the last time, read MoTP before you try to say something as fact. She Cleary says she Doesn't love Zack -
Aerith on Zack said:"Someone who's gotten along with so many girls can never become a lover."
And as for Cloud x Tifa..Well thats Purely your opinion, since no cloud Pairing is canon.
Just as i prefer Clerith to any other Cloud pairing although none of the couples will ever be canon, i just find Clerith to be much cuter and Beautiful than any other pairing