It's a bit inconsistent, but probably because the source material was written that way, with a soft retcon in between the material of seasons 1 and 2.

It was a simple Chaos vs Harmony faction thing at first, but then it got muddy with Kanna who was simply exiled to the human world. After Kobayashi confronts Tohru's father, the story shifts more towards humanizing the dragons and also showing how complex they are when they now live in a peaceful world.

The best way to interpret this is that Tohru has always been a bit of a rogue outsider among Chaos dragons because she's so much more powerful than most others, and also has always wanted some degree of companionship (much like Ilulu).

Elma, while being a Harmony dragon, was constantly taken advantage of because she's easily bribed and also lonely. The two met frequently enough that they became very close.

Then Tohru is "killed" by the humans, but actually fled dimensions, where she was saved by Kobayashi. A vocal hater of humans became enamored and obsessed with one.

Elma just felt abandoned. She wanted to drag her back to their world under the pretense that Tohru will cause trouble here, but it turned out (soft retcon) that Elma just wanted to monopolize the smoldering and guarded version of Tohru. She was irritated that Tohru keeps making more friends while generally avoiding Elma.

Since most of the dragons on earth are Chaos dragons (Lucoa being neutral), Elma became the outsider among the collective group.



My biggest takeaway this episode was how cool Shouta is getting thanks to his growing confidence in his magic. I guess his dad's concept of how helpful Lucoa is comes down to the fact that Shouta is becoming desensitized to normal levels of unexpected things due to Lucoa constantly harassing him with her body for fun. He stays cool under normal levels of pressure and quicker and quicker to react to chaotic events that used to put him into a tizzy.