
I'm a little disagree, hear me out. we saw Cain feelings for her from the very start and how fast he changes his mind after she helps him despite Edward didn't even trust her that much. then Cain starts to go more and more against Edward judgement and decision when it comes to her. he wanted to lock her so she is "safe" instead of trusting her ability and wits. while Edward, was worried about it too, decided to let her do what she wants to cause he trusted/respect her, unlike Cain. that was their whole fight back then.
and since then Cain and Edward fall apart, cause again Cain just want to treat her like a girl in need of protection that has no ability or skills to help herself. so it actually was predictable he will do that at some point, cause he thinks he knows it all about her while knowing nothing about her.
Idk man. It feels kind of out-of-character for Cain to betray Edward, especially for love. Before you cry heresy or "it's just fiction", isn't Cain supposed to be the closest to Edward? Why would he betray his leader and friend?
It's an isekai and the thing I most disbelieve is Cain's betrayal. *Gasp* Is Edward actually the biblical Abel??