she is constantly pining after Tatsuya while he is oblivious (or at least pretending to be oblivious) to her affections.
I still don't get why the first season skipped the summer break volume. Honoka confesses to Tatsuya there. He actually knows what's coming too when she's asks to speak to him alone. He turns her down, of course, but does explain that he's incapable of strong emotions and thus can only like her as a friend. She takes it well and gets his permission to keep loving him until she finds someone else.
Though the problematic thing about her feelings is that elemental families like hers were genetically conditioned to have absolute loyalty to their chosen master, who is Tatsuya in Honoka's case.
Not likable? She's always been a sweet cinnamon roll.
As for Eimi, she also had her own story in the skipped summer break volume. She even gets a not-Tatsuya love interest.
[Edit: just toned down your language a little. Errinundra.]