What is really ironic is that Emma's efforts to NOT change history is what ultimately got Regina so angry. Once Maid Marian was saved, Emma realized she could not just let her go live her life because it could change history and they decided to bring her to the future, ensuring nothing changed. If she had just let her go back to her family, Regina and Robin would never have been together in the first place and Regina would never know she once did an a different timeline. Even if they did still run into each other during the past year and she saw the tattoo, it would have been a case of lost opportunities. So Emma trying to do the right thing by first saving someone from certain death just for not ratting out her mother and bringing her to the future to ensure that save didn't change history led to Emma being blamed for everything by Regina yet again.