Between telling Miwa that Saeko might leave if she doesn't sleep with her, calling Miwa a pain in the ass, taking naked photos of Miwa, and now this; Rika is a huge shit-stirrer and a bad friend, even though she sorta helped them out once. I hope there will eventually be some falling out, even if it's just temporary. Meanwhile, Tsuruta continues to be a perfect friend.
It's interesting how jealousy has been a major theme this arc, with Saeko being jealous of people around Miwa, Kan being jealous of Miwa's upbringing, and Usshi maybe being jealous of 'normal' people having relationships. People are saying that they don't care about Kan's backstory, but I don't think the author was necessarily trying to make us sympathize with him. For now, I'd say he's there as a foil character to Miwa, to drive her to be more honest and assertive. It also shows how different people can end up just because of their circumstances. Saeko is still really guarded about her past, especially with Miwa, so Kan could eventually end up helping Miwa to understand where Saeko's coming from.
As much as some of the characters think that Miwa worries too much, it was reasonable for her to worry here. Sure, she jumped to the wrong conclusion, but it's not like she hadn't asked Saeko several times whether there was anything wrong. Here's hoping they actually discuss it honestly and that Saeko's jealousy doesn't lead Miwa back to being submissive and dependent.