>>113694836A lot of the Connie hate started when she got upset with Steven for not fusing with her to fight Aquamarine/Topaz and for sacrificing himself to save everyone. And like, I get it, Aquamarine would have BTFOed Stevonnie (they could've probably taken Topaz though), Steven did the noble and smart thing, Connie probably could've done better than ghosting him... but here's the thing.
Connie had been busting her ass to help Steven fight, and honestly, she'd been doing as good as a human could possibly do. The two had forged a pact to protect each other, it's not like Steven objected to Connie training and being a fighter even though she's just a human. Then, they began fighting as Stevonnie and... they were REALLY good. Stevonnie kicked Jasper's ass. Connie knew her limitations, but she and Steven both knew how good Stevonnie was in a fight. So then Connie tries to protect, freezes up, gets herself captured, and probably spends the next few hours fused into Topaz and being really upset with herself. Seeing Steven and the gems getting their asses kicked fighting to save her probably made her feel worse. So now, she's pissed. She's itching for revenge, and sees in Stevonnie a chance to get it... but instead, Steven sacrifices himself. Connie lashed out at Steven because she really blames herself for not being able to protect him, and who could really blame her?
But here's the thing: Steven forgave Connie. I imagine she knows she shouldn't have reacted that way, but it's not something that fell within the scope of the show to address.