So if you're not aiming for an ending focused on a girl, is it ok if she gets pregnant? Or will the game forcibly end on an NTR route for her? I don't quite understand if I need to be protecting all 3 or only the one I'm focusing on...It'd be annoying to have to go back a lot just to prevent some random pregnancy
If a girl gets pregnant not from you, its game over.
Here's what i could gather from playing it for a bit now, it has some stuff similar to their other game Tsumamigui 3, if you dont go for a certain girl, the bad guys wont do anything. So, unless if you follow a guide for the harem end, what i suggest is to just focus on 1 or 2 girls max, because its easier to defend them. For the girls you dont want to go for, or dont want ntr for them, just dont do the orange/pink stuff for them next to their bar.
Also, click on a girl when a bad guy is on the bar below and they cant to anything to them, care uses 10 energy and fill 1/3rd of the bar, aftercare feels the bar + the hearts and doesnt use energy, flirt gives an event and when used on the pink event, it gives the girl an extra red/hard heart.
About getting the girls pregnant, im not that far yet but i presume its later in the game because earlier you cant cum inside them without a condom for story reasons.