Well this entire episode, my main thought was “how could Michiru be so cruel as to stall the relationship between Isla and Tsukasa when Isla has so little time remaining.” I didn’t really consider that she had no idea what Isla’s lifespan was, so I guess she gets a pass for now. Other than that, Isla’s reaction to Tsukasa’s confession was pretty predictable. I’m still curious about how this show expects a happy ending given the progression (I still vote for bittersweet though).
It looks like Tsukasa has run out of time with Isla if Kazuki is dissolving their partnership. That being said, I can’t discount the possibility that this conversation is some sort of test that she’s giving Tsukasa to test his resolve and actually solidify his relationship with Isla. Does it make sense for her to call them into a room at night to end their partnership? Maybe I’m trying to read too much into this (I know it’s unusual for me to take the optimistic route).