Carefully lol .. Honestly 'missing scenes' isn't the real danger here. The game has no real over arching time limit. However once you set certain things into motion you will end up with other things happening. And if you ignore those threads without resolving them it can lead to the girls getting stolen or ntr'd. My advice would be is to if the game gives you any hints that your are under a time limit for something then do it. There are a few exceptions such as the trip to the abby. Even though the game makes you feel like you have to go NOW you can pretty much put it off forever. But if you leave Tia alone at Rumah while dasan is in charge for too long you will end up losing her to him. I've played through most of the game and there's only really a couple of 'catch' points.
1. You wont be able to have a serious relationship with emily if you are already in one with mia beforehand. Therefore if you want to go all the way with the mom you should get her done first.
2. As mentioned in Rumah you need to resolve things with Tia asap. Once she is your wanita and you've had sex you are good I think. I reccomend spilling the beans about Dasan and giving him the boot. Nyra won't be happy about it. But she'll come around if you keep screwing the various rumah girls in front of her
3. Timed events with Mira only really kick off once emily catches you together which is I think like the second time you kiss. You can take all the time you want to work on the emily relationship if you just leave Mira alone at this point.
Emily is the only one you can get hitched to at present. I've heard there's a polyamory system coming. But right now if you do marry her the other girls will be upset. So if that's not your thing then I'd reccomend holding off on the marriage until that update.