Friendships abroad have to be built deliberately in a way they never were at home, where school, family, and old colleagues did the work invisibly. The expats with rich social lives are almost always the ones who joined things: sports teams, language classes, hobby groups, volunteer projects, or religious communities. Repetition is the secret ingredient; friendships form from seeing the same faces weekly, not from one off events.
Expat communities play a real role, especially early. They offer instant understanding, practical help decoding the new country, and comfort in your own language. The trap is stopping there, because expat circles have high turnover, and a life lived entirely inside them keeps the host country at arm's length.
The durable pattern is a blend: expat friends for solidarity, local friends for roots. Local friendships take longer, often years, but they are what eventually makes a place feel like yours rather than somewhere you are staying.