I don't want it to go without saying that Mosskonbu-sensei's coloring is absolutely divine, and I'm grateful that they do it.
Now, while I can understand that in a broader scope of the class / school that keeping the marriage a secret is reasonable; but for as long as Akane and Himari have been close friends, I see no reason that it couldn't be discussed between the two of them.
So now we're in a rather "standard" situation where we have a second character that likes the male lead, has told the female lead as much, and has started to progress that agenda. Which leaves us with a female lead who is starting to be more uncertain in her own feelings; and I can only see this leading into someone's unhappiness.