A lot of women, when they're young, feel they have very good friends, and find later on that friendship is complicated. It's easy to be friends when everyone's 18.

Zadie Smith’s quote reflects on the evolution of friendship and how it can change as people grow older. When we are young, the bonds we form with others often seem uncomplicated and easy to navigate. At the age of 18, people tend to share similar experiences, such as school life or shared social environments, which can make it easier to connect and feel close to others.

However, as people grow and life becomes more complex, friendship can start to reveal its complications. The demands of adult life, such as career choices, relationships, and personal growth, can introduce differences that weren't as noticeable when everyone was young. As people mature, they often start to realize that maintaining meaningful connections requires more effort and understanding than they initially thought.

The quote also touches on the societal pressure that women, in particular, might face when it comes to relationships and friendships. Often, women are expected to maintain strong, close-knit bonds with their friends, but as life changes, these connections may become more difficult to sustain. This evolution of friendship is a natural part of growing up, as individuals change and develop their own identities, sometimes leading to the realization that friendship isn’t always as simple as it once seemed.

In essence, Zadie Smith is highlighting the impermanence and complexity of friendships as people navigate the different stages of life. It’s a reflection on how personal growth and life’s transitions can make maintaining friendships more challenging, particularly for women who may find themselves confronting societal expectations as well.