You hit the nail on the head. The discourse surrounding this series is just a gross misrepresentation of the series as a whole. Its very similar to the people who engage in the same kind of spreading of misinformation about kimizero. They cannot fathom a fml having past partners because they themselves have likely not had past partners. They would rather shift the blame on women for their own misgivings, and engage in spreading false information go portray the characters in not only a negative light, but also a wildly incorrect light. Thats why I have so much distain for the manga community, and the romance genre as a whole. People cannot see past a surface level understanding of characters, and refuse to engage in any discussion that goes against said surface level understanding. They want every main heroine to be the same prim and perfect representation of their ideals, and refuse to allow someone to tell a story that goes against those ideals.That's also ignoring Takaharu's role in things.
They were only dating for about three months; she was going through some stuff at that time, but he was oblivious and not paying close-enough attention because he had his head shoved into the mountain of work he had pushed upon him by others in his department, along with just generally being a closed-off guy.
Eventually, something occurred in Kyou's life that required she drop out of college. She never elaborated, but broke things off because she knew how stressed and busy Takaharu was, and didn't want to overload him.
And for his part, Takaharu told her in their last phone conversation that, no matter how much time passes or where they both are, she could come to him for help if she needed it.
And Takaharu was devastated when Kyou left his life. Lost all motivation to paint and draw, sunk even further into himself, developed chronic depression, shut himself away in his grandmother's house.
The moment Kyou showed up again was when the Sun came back on in Takaharu's world. Yes, Kyou is absolutely making full use of the standing promise from Takaharu, but it's not like he's been browbeaten or coerced into taking her in.
And you did mention it, but to reiterate: he wanted to. Desperately, even if he wouldn't immediately admit the reasons to himself. Even in their short time together and 17 years apart, they left a profound impact on one another--the sort of bond that brings people back together across time and distance no matter what.
It's really not fair to Kyou to try and make her a villain or bad person in this series. The number of people who disparaged her simply because she "dared to have a kid with someone not the ML" and treating her like cheating trash really does speak to some of the problematic elements of the manga community when it comes to the portrayal of women in Japanese comics.
This isn't me attacking you specifically or anything -- it all just bears repeating because both here and Reddit have seen the same inane "discourse" nearly every chapter that's been released, and it's honestly depressing because this series is just so good, from the plot to the art to the characters.
Ironically you see this kind of discourse in a more western world, and not in the origin of the works. If you look at Japanese comments vs English comments you see a much different discussion happening. It rings as ironic to me that the people complaining the most are the ones reading it for free, and not actually supporting the people creating the work.