Before, Douki-chan would look on in horror or despair whenever her rival flirted with her dude. She's come a long way since then to be openly glaring daggers at her rival now.
It's kinda obvious too that at this point, they're not actually trying to win him. They're just doing it for the shits and giggles of it all, making him flustered, her mad, and pushing them along a little.
The new girl is probably gonna join in with the trolling. Or she could still be a legit rival.