I like the look on her face when she finds out the reason he's avoiding her. I do love this manga, I'm not sure why it's hated so badly by many readers.
Although I enjoyed the extra chapter, I didn't understand what she meant by her color or her question in the last panels. It didn't ruin the experience, but it did leave me scratching my head in confusion while simultaneously grinning like a fool at their teasing/being teased.
I'm going to say nothing happened, because the mc seems like a decent guy that wouldn't have sex with his new girlfriend right after she collapses from drinking too much. That's like stepping a whole leg across what is and isn't rape.
I'd say 50/50 that they did the deed. Hero seems to be only attracted to the demon princess; however, there is a slim chance his natural urges takes command here.