Then again MC can say smiling all that shit just because he has always been an outsider, and inhumanely strong, so in that sense he's being a hypocrite. He even would've been brutally murdered and eaten by his own wife, if he didn't have cheat abilities.
If his family and friends would've been slaughtered and murdered by demons in many generations, and maybe even had his village burned etc., him being traumatized by that war since childhood, and didn't have an easy life with demigod powers, I don't think he would be spouting all those cheesy words with a smile to his ears.
Also it feels very weird, even a plot hole like, when the only one w/ conflicted thoughts, and being scared of the demon lord is Barirossa, and not any of the other girls. I bet you wouldn't be able to find any human in that world with no grudges and despise towards demons, if the war is as big of a thing, and has been going as long as we've been told.
Seriously the more you think of this, the stupider MC looks like, and Barirossa seems like the only one with rational brain and thinking, considering what has been happening in the past.
I know author wants to have this W H O L E S O M E shit with them all being friendly under the same room and shit, but it feels very undeserved, and even very illogical. People don't forget the past and it's traumas/grudges that easily. Then again this is just fantasy, and real people don't act like this, since they aren't "people", but shallow characters acting almost like people.