Out of all developments, "Chiaki becoming friends with Iino and sharing the worry of not being feminine enough to attract Daisuke" is certainly something I never expected.
I always thought Reiko is the closest Chiaki had to an official love rival for Daisuke, because it was never too blatant between the club members themselves (if they see one among themselves gets the lead, they only kinda comment on it instead of freaking out or bickering). Certainly did not expect Iino, a secondary character who started out as part of a Kaname gag that kinda developed into Kotone's foil. Although I'm not complaining about her developing beyond being part of a gag.
Also great to see her crush on Daisuke isn't a one-chapter thing that gets swept under the rug after the gag was over