Huh, that's a stupid misunderstanding. Or rather Marigold jumping to conclusions prematurely.
Marigold has so little self-confidence. I could imagine that in this situation she acted as she did, because she is nervous. I imagine she really does not know how to talk normally with Dale, because they have only argued when they met (although Marigold used to be much more eloquent than just "hissss" - I'm thinking of the "Some people have a life and do not play WoW all the time" line). I could imagine that she actually would like to be friends with Dale or appear cool to him or something like that, but since she's afraid of failing to do that so much, she acts in this defensive, immature way instead. Also, once you've done this for so long, it's hard to change your behaviour towards someone. I think in this instance, she was sort of afraid of him just leaving, maybe even half-expecting it, that when she didn't immediately see him when coming back, her brain went "Ah, I knew it! He just wanted to get away from me."
Does that make sense?