Look at the group photo again and ask who isn’t in it. Then text them.

Who is missing from a picture is information nobody announces. Somebody drifted, somebody was not told, somebody has been quietly dropping out of plans for months while the group still felt full. Absence is easy to overlook precisely because everyone who is there is having a decent time.

Pick one name and send a message with no agenda attached. Not a speech about checking in, just something small and ordinary, a memory or a question. Most people who slipped out of a group were waiting to be noticed and had assumed they would not be.