@Cannibal Lol, I knew what your response would be, so I stayed away from this thread until I mustered the energy (do not take this the wrong way, I like doing this, but it is exhausting). Well, here we go, I guess.
The theory that the crystal shortens your life is just that, a theory. They don't have any evidence that it shortens your life, only that it's painful to use.
"To win the battle, she stole a stone of power that the first witch had: the Magic Stone. It devours the life of a witch to overturn the laws of power." (Izetta's grandmother, in a memory, talking about the first Sophie, in episode 10.)
"The White Witch, the real Sophie, once said that the Magic Stone draws out the power of the witch by shortening their life. If you use it too much, you won't have long to live." (Said by Müller to Izetta, based on the diary written by his ancestors who were members of the court in Sophie's time, and were involved in the plot against her, episode 11.)
"If she crystallises all that magic at once, she'll die for sure." (Sophie's internal monologue, episode 12. This also indicates it is not just the duration of the usage, but the intensity as well, that drains the life from the user.)
You have no idea that Sophie was actually even killed. She just falls after failing to match Izetta's spirit bomb. Not once do we get a confirmation of her death, especially whether or not it was the crystal's life draining that caused it.
She unambiguously thought Izetta's move was suicidal, and given what we know about the Stone, this is indeed correct. Nevertheless, she tried to match it, given all the factors (nature of the Stone, the suicidal levels of energy being used, her previous usage of the Stone, and her cloned body (no, I did not forget her body was deteriorating more rapidly on account of the cloning)), the scene of her losing hold of her magic, her staff, and her falling down with that drained look on her face, can only be interpreted as her dying.
The only way you can take it as anything else is if you disregard several canon facts, and look at the scene with selective obliviousness. Not to mention the fall alone from that height (and they were above open water, in the middle of the North Sea, at that) would have killed her.
She only could have survived if, as I said, we disregard canon information, and then assume Izetta swooped in and caught her before she hit the surface (and just to be clear, I am not talking about drowning here, a fall from that height would be the same as hitting concrete pavement), and that is quite a scene to be completely left out and never mentioned in any way, shape, or form. Your argument is almost primary school level of 'not dead, we have not seen it'.
The state of her cloned body was a factor that made her weaker than Izetta, and quickened her demise, but it was the life-draining effect of the stone that killed her (again, given the above quotes, I really do not see another way to interpret this).
The original Sophie used the stone much longer than the clone and Izetta and lived for decades until she was betrayed and executed.
Now, this is actual, pure conjecture on your part. We are only told Sophie saved Eylstadt in a single war (and only one battle was actually mentioned), so we have no idea how long or how much she actually used the stone. Plus, those were medieval times. It stands to reason you do not need an awful lot of energy (again, levels of usage also play a part) to overpower mobs of barely armed serfs and a few hundred professional soldiers and knights (as was the standard for armies of the period), as opposed to going against tanks and fighter planes armed with rapid-firing cannons.
We also have no idea whatsoever how long Sophie lived before being betrayed, so I have no idea where did you pull these "decades" from. She still looked young when they seized her, plus, the whole reason for the betrayal in the first place was the Vatican, and the Inquisition. It is highly unlikely she would be allowed to live for decades in those times. Eylstadt would have been invaded into oblivion, as a heretic country, which was exactly the point King Matthias brought up when he signed off on the plot (episode 12).
No, it's set several years later. Not immediately after.
I was wrong on this one, I will grant you. Several years (and it could not have been more, given how young Lotte still is in that last scene) are still not the same as decades, though, so my original point stands.
Now, I understand why people do not like all of this, but still, the only way you can give Izetta and Fine a happily-ever-after for a long, long time is if you deliberately disregard canon information. There is just no way around this. And the thing is, Fine knows this. Remember the scene after the broomride, when they were on that mountaintop (episode 12)?
F: "What? But that magic stone eats away at your life, right? If you do that..."
I: "It'll be fine."
F: "You're lying. I can tell right away when you're lying! Especially when you're lying because you're about to do something crazy for me."
I:"I'm sorry. It's true that I might die. But there's something I want enough to do it anyway. A world where everyone can choose their tomorrow. A world where you can smile. Morecheesystuffbutfortheloveofgodsmyfingersaretired.
So give me the order to fight as your witch, Archduchess, no, Fine... And to end it all."
F: "No!"
I: "I've given it a lot of thought, but I couldn't think of anything else. So..."
F: "Izetta... Izetta... My witch... I order you... you..."
And the scene cuts to Fine breaking down and yelling at the representatives of the warring powers, and from her grief it is obvious she does not expect Izetta to make it back.