Why is it harder to make friends as an adult?

You're more selective (lower tolerance for incompatibility), busier (less time for bonding), and more geographically dispersed (fewer repeated interactions). Childhood forced proximity and lower judgment; adulthood requires intentional effort. But adult friendships are often deeper because they're chosen, not circumstantial.

Where do adult personality-compatible friends come from?

Repeated interaction with selection (coworkers, classes, hobby groups where you see the same people). Shared values (volunteer groups, religious communities). Direct introduction from people who know you both. Online communities (Discord, Reddit, Meetup) where personality similarities emerge. The key: repeated interaction + shared context.

How long does it take to develop adult friendship?

Typically 50-100 hours of interaction to move from acquaintance to close friend. For most adults, that's 6-12 months of regular contact. Fast-bonding friendships (instant chemistry) are rarer in adulthood but possible. Most adult friendships grow gradually.