OK sorry for double post, but with this wall of texts I kinda thinks its easier to separate just answers to others, and my "stream of mind" hehe.
So after I read the chapter now: This story is kinda confusing, but also there are hints of whats happening here and there.
Shizuku seems to have a reason to "run-away", either to actually run away or cause she maybe is ill and need to go abroad for some medical help that she can't get where the story is running. The "secret" phone call could support either of those, if she has some help for running away, or going for the medical stuff. Her big luggage she has in those latest chapters kinda support it.
From early on we know she loves MC, but cause he is retarded and cause of whatever is going with Takt, she somehow ended up dating the latter. But she doesn't have feelings for Takt, she wants her first to be with MC, but with MC and their both retardation, she didn't manage to "fuck MC" before it was time to leave. He once IIRC told her that till she explain the whole thing he will not touch her, he nearly broke his rule few times, yet she told him jack shit so in the end his rule won.
Umimi loves MC, but MC basically ignored her while promoting how awesome Takt is, to the point she asked Takt out, who agreed after he understood that she is basically another "love rival for MC". Their dating failed, she stayed confused, thou nowadays she kinda straightened her "resolve" that she loves MC and wants him, to the point she is willing to basically try and rape MC, which she tried to do in bathroom once, or to SA him in his supposed sleep, when she masturbated using his hands.
New girl - nothing to say really. Seems to be the only sane character, all other can go and die like some people say, but she should survive. She is the cutest, best looking in my eyes among the 3 girls. Has brain and uses it. Got interested in MC and pursues him, without retarded manipulations, NTRing, rape/SA tries, or other stuff.
Takt - seems to be gay, and love MC, but his family seems to be some kinda high placed political people, who probably hate gay people, so he needs to suppress it. Not sure if he asked Shizuku out as a means to keep MC single and waiting for him, or his parents need him to have a girl and forced him to date someone and accepted her, or both, or she needs some financial help with the possible illness she have and the deal was to be Takt girl/wife, which she kinda breaks now while seemingly running away.
MC - retard. Can't really say much more. He seems completely oblivious to all the girls and their feelings for him. It took him years and weird dreams (from early chapters) to realize he actually loves Shizuku, dreams and wake-ups from them that actually showed Shizuku that she still has a chance to lose her v-card with him and triggered the whole story if you will. He "loves" his friend Takt to the point he basically cock-blocks himself on every single possible opportunity he has.
At this point I hope that we either get a at least satisfactory to a degree explanation of Takt/Shizuku situations, and then them 3 somehow ending in a "proper way" aka MC and Shizuku being a couple and Takt coming out with his gayness looking for new boy, or still hidding but looking for a different girl to "console his gayness" if you will. Or MC leaving the two seemingly toxic friends who play with him like a fiddle he is, and end up with Yako - new best girl. Aka either we get explanations and MC ends in a normal healthy relationship with Yako, or we get explanations and the toxic trio ends up shuffled around but still somewhat together.