I mean technically Tidus and Yuna are broken up.

I can see Locke and Celes breaking up considering they have nothing really in common.

Cloud and Tifa are both in a dysfunctional codependent relationship.

I can see Squall and Rinoa having a troubled relationship, but I also feel they work for each other if that makes any sense.

I can definitely see Garnet and Zidane breaking up after she keeps catching him ogling the Alexandrian guards. I bet the whole army will have a sexual harassment lawsuit against him.

I feel Cecil and Rosa are the only couple with a functional relationship.