Could be passive aggressive behavior if she is not being truthful about the way she feels when she encourages and celebrates these things.Maybe she feels bad to say No, but deep down does not want it, so she leaves it to you to make the decision hoping you will make the one that she is truly thinking and when you do not she resents it. Some people do not say there true feelings because they feel they do not want to tell their partner what to do. What they really want is the partner to make the decision they really want, but without telling them. They feel if they tell them it is just like controlling them and they want someone who thinks the same. Could be the issue. However, could also be that in the moment she is truly happy, but does not look at the future consequences then when it leads to unpleasant consequences she is not happy and blames you. A lot of people remember what the other person did, but they forget what they did. Therefore blaming the other for the problem or issue with the new situation. I see you tried talking to her and she gets defensive. Try saying things like" Remember when we agreed on...." for example. It must be difficult for you because you would be worried about getting blamed for things that you both agreed on. Have a heart to heart and let her know that you want to make important decisions together and sometimes you both may agree or not, but you want to find a solution that works for both of you. However, it makes life difficult when she changes on you. Tell her that if she is not happy with a decision during the process to talk to you and let you know even when it is after the fact. Let her know you always want to include her in the decisions and never want to make them alone. You will be responsible for the decision and she needs to be as well whether good or bad. Try to talk in this matter that way she will put her defense down and listen. Do not blame or point fingers or say you said or did this or that. This only makes people defensive. Try talking in the manner I mentioned, so she can put her guard down. I hope this was helpful and brought some insight. I wish you all the best!