Something that doesn't make sense to me

In season 3 episode 1, Caroline and Elena discuss Elena's feelings for Damon and Caroline encourages her to talk about it and says it's very humane of her to have fell for Damon. Later when she found out they kissed, she's mad but specifically about the fact that Elena didn't immediately tell her, not that she kissed Damon. How come she was so chill about it? Especially when you see her disgust about it a season later.

Also how come Elena wasn't mad at all that Caroline slept with Klaus? I know people will say she was dating Damon so didn't feel the right to judge but still Klaus murdered her aunt, killed her temporarily (which led to the death of her bio dad), compelled her bio mom to kill herself, forced Stefan to become a ripper and used her as a bloodbag. It makes no sense to me that she would be so chill about it, regardless of whether her relationship with Damon would make her think that she is allowed to express it