This episode certainly gives plenty of context for Abby's dislike of Caroline. Caroline is straight-up rude to her on at least two occasions and if that has been going on for a while then her behaviour towards Caroline is understandable - jealousy aside.

I think Connor's declaration of love has to be the first time Abby realises he's actually serious, it makes a lot more sense that way. Despite acting as the comedy fall guy a lot, Connor nevertheless does give the impression of being more grown up this series.