So husbando, a totally normal human - is beating up an extremely superior, both biologically and mentally, demon simply because he was able to train for a few months? Yeah, ok, my suspension of disbelief is hanging by a thread. I still remember that this fight is predicated on the husband sticking his nose where it doesn't belong and letting an accomplice to attempted rape and attempted murder get away.
But the bigger question is, how are demons supposedly so feared if this guy is able to do this? Dude is in the boonies doing push ups and squats and can take on this monster owl- A ninja owl at that. A creature that has no doubt studied and trained against potential enemies and tactics (much like the ones it's facing) much stronger, faster and smarter than sir husbando and he's still getting his butt kicked by regular joe schmoe? Even worse if you tell me he was in the military or something, because then you're losing to people you're supposed to expect to fight.
Yes the fights look cool but a fight to me is meaningless if the story behind it doesn't make sense. This really reads like "he's the protagonist and a husband so he has to win" kind of fantasy.