Well, I'm not sure if it would go in this thread. So, forgive me if it started in the wrong thread name.
Who does the couple remind you of ? Their love remind you of who ?
My first thought always come to Kenshin and Tomoe from Rurouni Kenshin. (spoiler alert if you haven't watch it or read the manga.)
They're the first couple in my mind when it comes to analyzing common grounds.
Kenshin and Cloud are pretty much similar in attitude, except when it get to the TV series or his life after 10 years. Kenshin changed quite a bit, but yet, he feels not at peace.
I noticed similarities of how Tomoe changed Kenshin's world. Just like how Aeris changed Cloud's world. They brought out a side of them that Cloud and Kenshin would not even know that it exist. Even though, Tomoe did not always have on a cheerful attitude, her attitude was always somewhat positive and encouraging. And like Aeris having a red ribbon tied to her hair, Tomoe also had a red string tied to her hair. The thing I found most in common to Aeris is when Tomoe died, held by her beloved, and smile.
Its quite possible for Cloud to have a relationship with Tifa, but it depends on him only. Scars that deep, of where you witness your love's one death, ties you deeply. It took Kenshin quite a long time before he settle down with Kaoru, but yet, I don't believe he love Kaoru in a way that he loved Tomoe. When Kenshin had lost all hope, he turned to Tomoe, and when she smile, somewhere in his heart, he finally felt at peace. And even when his scar on his cheek faded lightly away, it was still visiable there. It stills ties deeply to him and those memories he have of her.