Wow. Based on the responses above, now I feel bad for enjoying this.
Ah screw it.
I thought it was a fun kind of play they were doing. We don't know how serious they were about all of it. And even if it doesn't last forever, it's pretty hot and sizzling for the time being!
Yuu needs to learn to be way more selfish. She thought it was selfish to push Touko like this, but really, her selfishness needs to come in the form of her saying she also wants to be with Touko. :| C'mon Yuu. Stop being standoffish.
The real problem for Tsu is being a non-siscon in a siscon universe. She should date the woman giving her advice, and her non-girlfriend should go "Find Her Sister on a Dating Site."
How do you know that Tsubomi is not actually a siscon in denial, and that her pursuit of Ayumu was partly out of a desire to "prove" that she's not a siscon?
This has been the slowest and angstyiest burn I've read in a looong time. And yet I keep coming back for more, knowing, somehow, that I probably will be disappointed with the ending no matter which way it turns because I've had to sludge through so much muck to get to that point.
I've heard that supposedly in Japan, sicknesses are more severe, for whatever reason. Even just a basic cold can be hard on the body. Maybe it's the climate or the self isolation for thousands of years.