I'll use names this time:
MC - Toru
FMC - Aino
CF - Tomoka (it was Chika in the WN)
MC's friend - Asuka
Toru accepts the engagement very fast and Aino is extremely happy about it. She somehow tricks him into saying he wants a baby with her and this triggers a complete change in her personality. She becomes like a totally different person, direct, naughty, provocative, bold etc. Basically very aggressive about her love for Toru!
She starts talking very openly about them being together and having a baby, so much that it triggers Asuka. She was the closest to Toru and is also a tsundere who didn't want to admit she loves him. Aino taunts her as she noticed her feelings but she runs away by lying she doesn't like him. Tomoka appears and Aino taunts her as well, which makes Tomoka try to 1 up her. She tells her she and Toru used to bath together, but Aino doesn't get even flustered, she just asserts dominance by saying they will do the same everyday and do naughty stuff in the bath! Yup, she does this all the time from now, flusters both tsundere girls by being open and direct about naughty stuff

Anyway, they get a call from the secretary who tells them they have to live together in a mansion. Then it becomes veeeeeery ecchi. Aino doesn't hold back and takes a bath with Toru, even going full naked and forcing him to touch her boobs and butt. Then she continues the same in the bed (there is only 1 bed in the whole mansion, so they have to sleep together). Toru here stops being a doormat but doesn't go all they way because he thinks is wrong to do it yet.
The next day while going to school they are all lovely dovely but run into Asuka. Aino again taunts her, but this time she succeeds and breaks her tsundere persona. Asuka admits she loves Toru, which shocks him since she never seemed like that in front of him. But then Aino tells her about the naughty stuff they did, and she runs away calling Toru stupid.
At school their open lovely dovely triggers Tomoka, and Aino again taunts her by describing her what they did in the bath and bed. This girl does not hold back at all



Tomoka then decides she will move in with them to monitor them and stop all the naughty stuff. Aino is actually cool with that, surprisingly it's like she wanted that all along. Now here is the fun part... Remember there is only one bed

So they start living together but Aino becomes more direct about nauhty stuff infront of Tomoka which starts breaking her tsundere persona really fast.
As Toru goes to take a bath first, he starts thinking about how all of this is not normal and how he doesn't understand Tomoka's motives. But then Tomoka enters to bath only wearing a thin towel and joins him. Here we find out a bit of the backstory... She admits she still loves him, and the reason she hates him is that he gave up on her so easily. She actually didn't care about the incident and didn't want to break thing of, her father did it on his own. It's not really explained what happened in the past but from what i got, they were kidnapped as kids and Toru managed to escape but left her behind. This made her father angry and he broke their engagement. I also think his escape was the reason she could be saved, but the adults forced their opinion "you abandoned her" on him, in which he gave in and believed so too.
She also tells him she has a potential new fiancé, and asks him what to do, will he let her go like that. He doesn't know how to answer but kinda tells her he will be sad about it. This strengthens her resolve and she decides to fight Aina for him... Aina then enter the bath, full naked ofc, and we get a ton of naughty scenes. Girls fondling each other and... you get it. Toru you lucky bastard

Then the naughty stuff continues in bed for a little bit, all 3 of them have to sleep together and Toru has to be in the middle ofc.
The next day Aino wants to go on a date but Tomoka objects, which makes Aino invite her to. They go to the karaoke and compete for Toru. Tomoka wins but does not use her "do what i say" prize yet. After leaving they bump into Asuka who is stuned seeing Toru with 2 girls around his arms. Aino and Tomoka taunt her, and while she is flustered Aino invites her to live with them while still asserting dominance by saying Toru is only hers. Asuka suprisingly declines but does not back down, she openly declares her love for Toru in front of all them and declares she will win his heart and take him for herself. Toru is confused as hell by this situation
And that's it for now. Maybe i'll check out the LN over the weekend, it has 3 vol translated.