Welp, I think the friend is actually trying to protect Meguro because this time she had the time to react.
Think about it, usually she says yes to the first random guy, they have sex, the guy dump her. Even if the friend try to warn her, she doesn't really react. But there Meguro stays with the same guy for several weeks. So the friend goes directly to confront him. If she takes weeks to do something, she obviously couldn't do anything all the previous times.