Su does not understand her feelings, but her actions still say "jealous." Mentions needing to remind students to be faithful (I wonder why she wants to do that); immediately reminds Tang Ran that she won't be there when the prospect of a sleepover comes up (of course because she wants to gauge Tang Ran's intentions).
Then that straw bite and she even goes nuclear by adding Tang Ran to the expedition team. I'm sure in her mind, she'll explain it as a needed teaching opportunity. She is going through it but in her refined kind of way.