Aerith met Cloud during a very troubling time in his life. His memories were jumbled & he was being controlled by Jenova’s cells. However, despite these challenges, Aerith was able to reach through to Cloud’s core & leave a long-lasting impression on him — one that he carries with him to this very day. One needs to look no further than Cloud’s behavior & actions after regaining his memories to see how much Aerith meant to the real Cloud: he remembers her often, fights to avenge her death, carries grief & guilt over not being able to protect her, and eventually begins living in her Church. Zack’s memories and Jenova’s cells weren’t enough to stop Aerith from reaching Cloud’s heart. Zack’s memories & Jenova’s cells weren’t enough to stop Cloud from truly caring about and developing a love for Aerith that has stayed with him forever. All of this makes the case even more compelling for Cloud x Aerith because Cloud developed a love for Aerith DESPITE Jenova’s cells and DESPITE Zack’s memories — a love he has carried with him long after regaining his memories. This is a testament to how much Aerith meant to the "real" Cloud because she was the only one able to reach Cloud’s core despite these challenges being present. This left an eternal impression on Cloud — one of a love that could never be. This causes Tifa to forever be jealous. Why? Because Aerith will always be Cloud’s #1 choice deep down.
