Cudi's part is pretty simple: Slowly realizing that as time changed your significant other has as well. "She said she don't know me, anymore." Since love is such a strong feeling, and they no longer have love for each other, they give the opposite strong feeling back. "I think she hates me deep down, I know she does." They part their ways, he's left heartbroken. Than she comes back saying "I can't stop missing you." Which by then he moved on but enjoys knowing she got hurt too "it makes me feel a bit complete." He has some advice that she will move on like he did "Knowing someone you love don't feel the same way about ya. Memories, they soon delete."
Kanye’s part: Play on words. Aaliyah = rnb artist who passed away. "Don C says she cool, but don't let her fuck ya cream up. Monica Lewinsky on the jet, she take you to the cleaners." Lewinsky the lady who had the scandal with bill Clinton. So possibly meaning he shouldn't be with this young lady but he is comforting her saying they're scandal is "Clean" compared to Monica's. The love just like in cudi's part is dying "but all good things gotta come to an end. She let it go to her head." (enjoying the luxuries of money but he assures her HE provided her with it all "No, that mine, 'ria."- ria is a nickname for maRIA) and THE BEST PART OF THE SONG "height of her shopping was writer's blocking me. I couldn't get my shit out anyway, I hope you die, 'ria." He is telling her to fuck off and die. So he can get his shit (music) out like "diarrhea". haha.