This depends on how far your relationship has progressed. If you really want her, then give her a wedding ring. After all, she is 27 years old, and she is not young anymore. Girls of this age also want to have their own family. Wedding rings represent a lifetime commitment.
If you haven't considered getting married yet, you can also give her a personalized engraved ring. Although it is not as romantic as a wedding ring, it is also very good. It can be engraved with your girlfriend's name or blessings for her. It is also very romantic for each of you to have one.
Or if you have an heirloom in your family, you can also give it to her with the consent of your parents. Heirlooms are passed down to one's family. In this way, she will understand your feelings for her, and she will definitely feel safe!
The next step is to make a girl feel safe with you. You have to enrich yourself and let her see your maturity and stability, so that she will naturally feel safe.