Final answer:
The exchange of rings between Amber and Heidi signifies a nonverbal commitment in their relationship, symbolizing a lifelong partnership without the need for legal validation.
Step-by-step explanation:
Although Amber and Heidi are not able to marry legally in their state, their exchange of rings is a nonverbal example of commitment in the stable stage of a relationship. The gesture serves as a symbolic binding of their lives together, embodying their intention for a lifelong partnership despite the absence of legal recognition. This act reflects the broader social pattern where cohabitation and non-traditional unions, such as servinakuy in Andean culture or same-sex unions before legal recognition, often serve as precursors or alternatives to formal marriage, showcasing the adaptation and resilience of social customs surrounding marriage and commitment.