Kana's strong sense of responsibility pushes her to put in serious effort in her career, making her the most talented member of B-Komachi. The same sense of responsibility has led her into a bit of a self-deprecating negative spiral. The same sense of responsibility has lead her into living alone, losing the direct support of her parent. Oshi no Ko does a good job showing how this sense of responsibility can lead to success and lead to ruin.
Ultimately, though, it doesn't make much sense to be an idol if you're not enjoying it. Ruby's pep talk is a first step. Hopefully B-Komachi can help Kana develop a healthier and more productive attitude towards the entertainment business.
Also Aqua is making the situation unnecessarily complicated with his antics. Though his plan did mostly work! He was a bit careless at the end there. It's cute that Kana basically falls in love with Aqua for a second time. How many times can we go up to!?
I'm looking forward to the next episode with their first performance. I hope Ruby's pep talk was enough to get Kana through the performance, because I don't like seeing Kana dwell in negativity. Either way, I have a feeling that the author Akasaka and the animation studio Doga Kobo won't let us down.