It's interesting how some readers have an entirely different view on this than me. Where I see them overcome the troubles and grow closer again and again, even if everything isn't perfect yet, and consider the new troubles a chance to solve another problem, they only see impending doom. I've decided to name this the Bakarina Syndrome - due to remembering the original one-shot, people are so focused on the doom flags that they completely fail to see all the more positive developments this series has had.
Thank god some people are reading this similarly to me. Even if we are getting the same ending as the oneshot, the relationship they have in the serialization is completely different.
In these past few chapters we've seen that they do care and are serious about each other: Both of them seemed self-consciously worried about souring their relationship, Miwa with her gloomyness/passiviness and Saeko with her jealousy. Also in chapter 19 Saeko introduced Miwa as a girlfriend to her mom, while Miwa offered to dry Saekos hair after noticing she had been hurt by being made to remember middle school. Furthermore Miwa is showing initiative in not only improving herself so that Saeko doesnt tire of her(ch 15-16), but also in uncovering Saekos past traumas and making sure she stops distancing herself whenever something that bothers her comes up(chapters 17 to 19).
To me this makes it seem that they are in fact emotionally invested in each other, something the one-shot outright denied they were.They arent struggling to fall in love with each other, but with breaking out of their past habits and experiences so that they can keep a healthy relationship(which they both seem like they want to do!). So, regardless of how it ends, this is completely different from the shallow relationship they had in the one-shot where they broke up apathetically without even trying or feeling anything.