"then I would never choose a future where I ignored his wishes and turned back to stop him."
Tia setting Ed free because she wanted him to keep chasing his dream (actually getting back home) over her own desire to keep him there sounds like a selfless true love to me. My heart goes out to her who seems to be getting left behind in this world. I can not see a way for her to follow him across his world-hopping journey.
I absolutely love how Tia immediately started casting a super powerful offensive spell the moment Gonzo put her down on the ground. She didn't even let the enemy finish trash-talking them, she just went for the kill straight away, even destroying the barrier behind in the process. Walls? Gates? Guard? What's that? There was nothing left of him, damn.
Ed finally got to show off just how pretty damn powerful he is. These demons consistently underestimating him were their downfall, and he fought with little regard for his own body's safety, including using a skill that would normally kill him at the end of a time limit, because said time limit (if I'm not mistaken) is longer than the timer that would unsummon him from that world.
Combine this with what IIRC he said before: that his body is always perfectly restored to a certain state (including biological age) whenever he comes back to the space between worlds, means he can abuse that deadly skill at the end of any world run, so long as its timer doesn't expire before he's unsummoned out of there.
EDIT: Dear novel readers, stop replying to me with spoilers I didn't ask for. I will not read any of them; keep your spoilers to yourselves.