I loved that there was a sequel and I think people are writing off their relationship too early. It's new and they just only started to be more communicative about their feelings. There's a lot that could be explored and it can work out if they just keep being honest about their wants and needs and can find a good compromise.
Risa was upfront about her polyamory in the beginning and Yuka thought she was OK with it until she wasn't (heck she knew about this side of Risa since high school). Risa hasn't slept with anyone since living with Yuka and doesn't feel the need to currently so it can still work out. And if it doesn't (since Risa hasn't promised anything), then that's OK too and they can find someone else who fits their needs better.
I really enjoyed the two chapters and I hope to see more of these two!