In J.D. Robb's book "Promises in Death," the character Eve reflects on the nature of marriage, suggesting that over time, it transforms the barriers between partners into transparent surfaces. This metaphor implies that as relationships deepen, individuals become fully aware of each other’s inner thoughts and emotions, leaving no room for deception or hidden feelings.

This perspective highlights the intimacy that develops in a committed relationship, where both partners are constantly visible to one another. The concept of walls turning into glass signifies both vulnerability and trust, emphasizing that true understanding can strip away facades and reveal the core of each person.