I think you're pretty spot on.
I don't see this as a big conspiracy, planned in advance. I don't think she left early cause EA creeped her out and I don't think the calls on the walk were giving hints that she was in trouble. Like many 23 yr olds she seemed totally obsessed with HF. Weren't there 25 calls or texts to him that went unanswered? I think she was fuming and was going home to see what was up with that passive, aggressive little $&@/. HF.
ETA JMO