i kind of think the same. Iruma's mindset is not really oblivious but rather different due to his upbringing. he has Alice and Clara as first friends - best friends so he will not likely think of romance with Clara or any of the demon girls. he is human so even unconsciously he might avoid being eaten? ヾ(╹◡╹)ﾉ
Exactly my thoughts as well he is different he was born under different circumstances. Like you said his mindset is different because of how he was brought up and what he went through during that time period. Also as off right now he is a human and as we know the demon have a way longer life span so idk how that will ever work out if it ever dose happen. But regardless I really love the manga I don’t really think it further needs to build on the romance aspect. It’s great the way it is right now.
Still believe iruma will Friend zone them but idk if it will really happen because as of now you don’t get the feeling of any of them being a love interest. If it never happens I wouldn’t mind because I think the story is Progressing fine without it. Hopefully it doesn’t happen because at least for me I can’t really see Clara with him at all. I just see her as a motherly or sister type character , Charm wise she is adorable but liked I said can’t see as a love interest. So I really hope the artist sticks to the conquering the demon world aspect for the time being before the talk about love interest comes up if it ever happens.