I think this is testing Satomi's trust, since she got hurt so bad by Mikami. This is an opportunity for Kanji to show her that he DOES come back on time. And Kanji really does need Rika to give up.
I think Kanji / Satomi makes sense. They're both naturally quiet people who don't need big flashy passionate romance, and in fact are exhausted by it. Kanji was already thinking about breaking up with Rika before she left. It may be lackluster by One True Love dramatic standards, but it's much more realistic.
That said a Rika/Kanji pairing is also realistic, with Kanji being miserable but staying out of a feeling of responsibility because he's needed by someone he doesn't love. I've seen that type of relationship in real life too.
This chapter was very lifelike. I feel bad for all six of them, even Mikami for a change. Because none of them are "wrong" in their feelings, just sometimes the feelings don't line up the way people hope.