That was lovely. Sumika is very attentive and fully understands Kanako and what she's going through. Kanako has to face her feelings. She's gotten comfortable being in a place that postpones the rejection she unconsciously knows is likely inevitable. Sumika wants her to face this first, then maybe after the dust is settled her and Kanako can come back together, just as the storyline said.
This series actually has such interesting characters, with actual depth and it has them interact and talk in meaningful ways. It's not afraid to put it's characters in uncomfortable or unfavorable positions and to have them act in disagreeable but understandable ways. A lot of manga are afraid to make their characters even potentially unlikable and the story's depth often suffers for it. In contrast, this series focuses on the nuance and emotionality rather then the simple labels that people generally run for. You can tell that the author really cares for each of their characters but doesn't treat them like perfect moe dolls. They're all their own MCs. I really enjoy Kanako's dilemma and struggle. Her relationship with Sumika is amazing. The outcomes are also varied in a way these types are usually not. I get more impressed as it goes along.