Seol-A called No-Rae because, I believe, she remembered about her while looking at Kyung-woo's eyes. And she was like, 'Damn, I want her to get me home, not this guy'. I see this as a further development of Seol-A's feelings.
Honestly, I don't see the guy as being able to assault Seol-A anyhow. Maybe another girl, but not her. He's a chicken after all. He hoped Seol-A would've been more playful, had she not become so wasted. He obviously miscalculated the amount of alcohol she needed. Had she drunk less however, she wouldn't have been reacting to him at all. And apparently he wasn't going for the sleeping beauty scenario. To me it's pretty clear nothing would have happened if No-Rae hadn't come. In the worst case, he'd have left Seol-A alone in the bar.
But No-Rae came, and her bashing herself, I took it as her accepting the existence of her feelings for Seol-A. I don't think she was disappointed at saying too much to Kyung-woo, she was rather 'I couldn't help but run for this girl no matter where she is and what hour it is, even though it wasn't really needed. Damn, I'm so in love.'
I think the chapter really delivered. I'm also curious about No-Rae's words to Kyung-woo about being direct with his feelings as opposed to the shameful tactics. Was that some kind of foreshadowing for a confession from her side? I honestly didn't expect anything in the next 10-20 chapters. Very interesting to see how she behaves herself now. At least she didn't fall to kissing Seol-A while the girl was asleep.