The reason why the woman doesn't want to get married is because she feels that the current situation is not suitable for marriage and lacks a sense of security. It may also be because you haven't formally proposed to her yet, and getting married now is too hasty.
1. I don't think it's suitable to get married yet
Getting a license means getting married, which means that two people are no longer in a relationship, but have formed a family and must bear legal responsibility. If the woman does not want to obtain a marriage certificate, it is mostly because she feels that your current state is not suitable for marriage, and your work, life, money, and other aspects have not yet reached a standard for marriage. Although your relationship is currently good, she does not want to go any further. It is good to maintain your current state.
2. Lack of security
Girls may not want to apply for licenses because they are dissatisfied with their current state, lack a sense of security, and are afraid and worried about the future. If you form a family and encounter various conflicts in the future that can no longer be resolved by breaking up, it feels like you haven't reached her psychological position yet.
3. You haven't proposed yet
If a girl doesn't want to apply for a certificate now, another reason is that she is missing out on your proposal ceremony. Many girls think that the sense of ceremony is very important, and they want to apply for a certificate directly before you propose to them, which is too hasty. So boys can prepare a formal proposal ceremony.