This has always been my biggest problem with the humanity switch because the show plays if off like as soon as you flip your switch you just become a total dick. Stefan, Elena and now Caroline all have emotions with their switches off they just don't care about remorse, empathy or other's feelings but I feel like humor, anger, jealousy and rage all come out when they have their switches off.
Just going to jump in with my opinion on the whole Stefan/Caroline debate, while I don't think it's Stefan's fault for not telling Caroline his feelings at her Mom's funeral it wasn't what he said that upset Caroline it was his absolute fail of a poker face when she asked him what category he wanted to be put in. He didn't have to say anything she read it on his face he was planning on "pulling the rip cord" and that's what broke her heart. Stefan is the one who was initiating all the romance between them after her Mom got sick, Caroline was fine just being friends with him after 6x10 he's the one who initiated all their romantic encournters. He followed her everywhere, he kept finding ways to hold her hand and touch her, he kissed her after telling her he wasn't doing everything because her Mom asked him too. I just feel like both of them let Damon's advice get into their heads too much and it was just an awful sequence of terrible timing but not really anyone's fault.
Stefan blames himself because he's Stefan, but he also shouldn't have pushed her after she said if you push me I'll become your worst nightmare (unless Elena didn't tell him this, which is stupid on Elena's part since she knew Stefan was going to try and break through to Caroline.) I think Stefan knows he's not the actual reason she did this he just thinks/knows he could have stopped her (and Elena affirms that as well) if he'd just told her the truth. He definitely wasn't a "total ass" at the funeral but that has more to do with No Humanity Caroline being a dick to everyone.