I'm calling it cycles because there's definitely going to be more than one trip into the past. Hell the trailer itself had two separate time traveling montages (one from the first where the prince got ganked and a second under less specific circumstances). And like in Majora's Mask, each time you see the phrase "Dawn of the First Day: 72 hr remaining." you're starting a new 3 day cycle. Seriously, this isn't moon logic here.
I'll grant you that there are two time travelling sequences in the trailer, the first with Toki in the bloody wedding dress and the second in plain clothes. I still have no idea where you're getting cycles from. In fact given that they apparenly take place under different cirumstances doesn't that speak against simple cycles?
And when you say "like in Majora's Mask"...what is like Majora's Mask? Where is the common phrase here? There's nothing like that.
Another aspect of the trailer that nobody seems to be mentioning is how it's pushing the romance aspect and talks about having to choose between Toki and Towa (wait, aren't they basically the same person...). That seems like a weird direction to take things in. There was one brief segment in the trailer (though I remember something similar from earlier screenshots) that almost looked like a dating sim. But since the rest of the game seems to be from Toki/Towa's perspective...what's up with that?
You're right. I probably should be trying to draw parallels to the Back to the Future Trilogy instead. I say this because now that I think about it MM was more about using time travel shenanigans to make multiple attempts at stopping a single and particularly devastating catastrophe. The trailer looks more like there are going to be multiple smaller catastrophes that occur at a particular event where using time travel shenanigans to fix one leads to the creation of another (based off of what the trailer showed, it looks like in one instance the main character dies protecting Launch/Lunch/Female Lead #1 and she ends up coming across the macguffin needed to pull off time travel shenanigans, and another instance of the same event (the wedding) but this time Female Lead #1 is the one who gets ganked and (just a guess from this point on) it's up to Female Lead #2 to take over(/guess)) much like how in the BttF trilogy when Marty McFly goes back to 1955 to escape the bad end Doc Brown met he screws around with time which winds up both saving The Doc and improving his own circumstances which leads to Doc Brown visiting the distant future of 2015 where Marty must right his kid's wrongs but this leads to Biff getting a hold of the DeLorian for his own nefarious purposes which forces Marty to retrace his steps until he fixes the damage Biff does.
The tl;dr of the parallel I've been trying to make here is that every time time travel is used to fix something, something else tends to break and requires further time travel to fix. Admittedly my initial assumption was that this was operating under a 'one problem that refuses to fix itself and needs multiple attempts to find and enact the exact requirements necessary to fix the problem once and for all' which is a time travel trope used by both the video game Majora's Mask and the movie Groundhog's Day, hence my initial references to the former.
As for the other aspect of the trailer, I blame my lack of moonspeak-foo. That said, this basically ties into the theory I stated above. There are going to be multiple instances of time travel, and in some instances the Leading Female #1 will get replaced by the other Leading Females as party members with their own gimmicks (LF#1's is multiple personalities, the others are yet to be disclosed). I'm going to bet that the game's plot will basically consist of the main character's (i.e. The Prince currently named The Protagonist) death at the wedding followed by Launch's (and other female leads') multiple attempts at going back and getting the past The Prince i.e. The Protagonist to help her save him while also showing us their relationship increases in an effort to put the beginning at the end while also giving the player total and complete agency over the relationship.
To tl;dr my theorycrafting, the reason why we never see The Prince in any screenshot is that we will almost always be in the past The Prince's PoV (at least on the time excursions where his death needs fixing, it'll be the present one for future laps for repertoire building with the other members of his eventual harem). At the end of the game, the player through The Prince gets to choose who to marry out of his potential harem.
All in all, I almost think this game is taking not only the idea of hand drawn characters on 3D environments from Thousand Arms but its sudo-date sim nature and its combat system with alterations made to make the rearguard support the PoV and always The Prince named The Protagonist.
Holy shit, that's a lot of words for my pessimistic take on an almost assuredly disappointing game that I'll never play
due to it never leaving Japan