While I agree with your take on most part, in Iemori case, it was a bit different imho.
I guess its because the MC (iemori) is a pretty good, naive, dense and unexperienced guy with kinda low self esteem, he thinks the girls really just treating him like a friend. He felt flustered because they're cute but thinks it was just them treating them normally as a friend. He only finds out kanna likes him on the latest chapter.
For himari, he basically asking her help to help his love towards Kanai, so he told her already. Besides, once again, Iemori, having a low self esteem, would never imagine himself being liked by someone as popular as Himari (also kanna cuz he said multiple times how she's cute and why she's spending time so defenselessly with him)
So in Iemori case, its more like the fact that those girls likes him never really register in his head so in his POV, there's not really any needs to tell them out of nowhere....
Well... but if he continues this way even after knowing their feelings, ur take would be completely valid thoughhh.
If he is in love with Kanai he rly should tell other girls that he likes her, I know it's kinda weird talking about you crush to them, but damn I rly don't like this.
I don't rly care which girl is endgame, but I'm sad for the other two, like Himeno is super happy he will come to her house during Christmas, not knowing he is in love with someone else.
I hope he will tell her now that he likes Kanai, and asks her if it's OK to tell her he works for her, because he wants to come clean about his work, and she realizes it's not meant to be.
That's why I don't like stories with multiple love interests, I feel sad about the guys/girls who are rejected or have to give up early because they realize mc is in love with someone else.