Responses
I agree, not every story has a perfect ending and while I really wanted they to be all happy, it was bound to end up like this. Aqua choose revenge in this life and he maintained this state until the end, so in a way it was expected.
Tho I agree with others who said that the ending was kinda rushed and would've loved seeing more about Ruby's character development. Or some extras about an au where everyone's happyʕ´• ᴥ•`ʔ. Gonna wait for the fanfic writers to come up with something.
I guess, no matter what happens, history is bound to repeat itself. The ending was meh but I don't know. It seems fine to me. Nothing is perfect and Aqua didn't create this life-impacting change in Ruby that didn't make her change. She admires Ai for a long time and the more she learned of her mother, the more she understood. To me it's like she's following in the steps of her family because she loves them or whatever, and it's the only thing she's holding onto. But it could've been better.
I guess I'm more happy that Aqua is finally at peace and he isn't dealing with this internal conflict of two lives. He's free of everything and that matters to me ╮(￣▽￣)╭