conceal.

the ice palace and fancy bridge and sudden connection with her abilities is, in my opinion, not so much her being able to control them but rather a combination of a) a giant weight being lifted off her chest due to being alone, and b) a significant lack of worry about other people because here, the only person she could hurt is herself. it was a highly euphoric moment -- she's free, everybody's safe, her imaginary happy ending.

and then what happens? literally three people arrive at elsa's ice palace and she shoots her sister in the heart, creates marshmallow who would probably have killed them had their thinking not been quicker, and everything goes to shit. her anxiety comes back. i'm a monster. i'm not under control. conceal. don't feel. don't feel. don't feel. 

when hans and company comes, she's even worse! her ice palace shifts to reflect her mood, yellows and reds of fears, anxiety, and she's so out of alignment with herself that she was literally prepared to kill a person -- maybe two, maybe more -- until hans stepped in.

literally six people arrived at her palace and elsa lost control of herself, her ability.