Sow and Friedman open by contrasting the largely effortless, proximity-based friendships of childhood with the deliberate ongoing effort adult friendship requires.

Why adult friendship is structurally harder:

• Proximity (school, dorms) that once made friendship easy disappears as adult life scatters people geographically and by schedule
• Careers, romantic partnerships, and family obligations compete directly for the same limited time and attention
• Sustaining closeness now requires conscious choice and consistent effort, rather than happening automatically through shared daily context

This opening frames the entire book's project: taking adult friendship as seriously — with the same deliberate investment — as romantic partnership typically receives.