As much as it's obvious to us the readers that she's having second thoughts about Saku on some level, Rikka is like, super obviously having a good time with Aoi and it shows. It's kind of weird Rena said it sounded forced, cause it really didn't. I mean we can't see the inflection in how she spoke but just looking at her skipping around so happily moments before should have been an immediate indication she's not super openly concerned with things.