[quote=@rush99999]
Why would Jub be blaming himself?
[/quote]

Survivor's guilt, basically. Both he and Brut went out on that boat and got attacked by the merrows, but only Jub made it out. Brut was (in Jub's mind) this really powerful unstoppable force, and Jub is this squishy wizard. In his mind, he's gonna be like "I really shouldn't have been the one who made it out of that situation"

... this is assuming, of course, Jub does make it out of this. We still don't know, obviously xD