Well, just shotgunned the whole series in a day. Hello folks! What a ride, huh? I just had to come in at the end of a major arc.
Reading through your comments, I'm really glad to see all the interest! None of my friends are following the manga so I have no one to talk to about it, even though some are watching the anime. I'm still holding out hope for the OT6/harem ending, for reasons people have said here - there have been so many points toward it, even with the now-emerging themes (mostly with Nino) of growing up and growing apart. In any other series, I would expect that to be foreshadowing for Fuutarou picking one of them and the others accepting it as proof of being grown-up adults now, but the theming has always been grow and change so we can complement each other even better - not grow and change so we drift apart. The girls are all whole characters and people on their own, of course, but they're also 20%. Everything from the finals mini-arc, to the bonfire legend, the cake sharing motif, to the friggin' title of the series - it's all hinting at being together, no matter what. And it was good seeing that photo with their grandpa reinforcing that, too. No matter what happens and how heated things get in the future (which is to say, the rest of the series), the girls will always have each other.
I'm just gonna applaud Nhani's interpretation of the multiple wedding dresses, too. Those things aren't easy to put on, so they can't quick-change, but one dress for each of them would be just about right. Actually, we haven't seen the other sisters yet, come to think of it. I believe we've only been shown the same sister in all the flashbacks... but my official guess is now that all of them are wearing wedding dresses. I don't predict we'll have a problem with their dad. If he's agreed to the marriage of one, he may as well have agreed to the marriage of any of the five - or all of the five. We've also already been shown that he doesn't seem to be that bad of a guy at heart. He just doesn't like Fuutarou because Fuutarou's insult to him hit him in a sensitive area and was basically 100% accurate, and I think the girls' dad knows that.
Edit: One thing I will say... I'm glad the author included that little bit that implied that Ichika talked things out with Nino and was open with her, though it seems like a weird thing to do off-screen. Ichika was shown in a light I didn't like in this arc, where her sneakier side and tendency to lie came through, and I was upset when she tried to cut down Nino's feelings - even if she was panicking and wasn't doing it maliciously. I know she wouldn't have wanted to leave things like that herself, so I'm glad that air has been cleared. Still knocked Ichika a few points down on the Best Girl rating, though.
Also, the author is actually very good about leaving subtle clues when "mystery" elements are introduced. It's like a mystery novel - the clues are there if you know where to look, and are probably clearer upon a second read-through. The only time he's actively misled us is with Ichika's hurt ankle, I think? Heck, you can see in this thread how many clues there are to pore over already. The answer is sure to be something consistent with the breadcrumbs, we just don't have enough breadcrumbs yet to say for sure if the best ending is the one we're getting.