I had a feeling she’d do the whole ‘I’ll back off for my sister’s sake’ thing. Unfortunately, she doesn’t realize Chitoge is still in the running. Just because it’s a ’false love’ doesn’t mean it can’t become real. And all the Chitoge-centric chapters, especially the most recent one right before this festival arc with the ribbon search, really hammered home the impression Raku is starting to realize he might have caught legitimate feelings for her while faking a relationship, just like she did.
I dunno how soon it might happen, but when it does, the inner conflict for him will be quite something. He’ll be wracking his brain on who he likes more, and if it really does turn out to be Chitoge, he has to work out if she really feels the same back through all that tsundere energy.