Recognize what makes this moment difficult
Acknowledge the event directly without turning it into a lesson, comparison, prediction, or silver lining. For a message about how to congratulate someone on graduation, use this factual base: name the milestone and, when you know it, the effort or meaning behind it.
Offer support that can be accepted
Offer one specific form of practical or emotional support and make clear that no immediate reply is needed. Offer warm recognition and let the recipient decide whether they want a call, visit, gift, or quiet celebration. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Follow their pace rather than yours
Do not make assumptions about pregnancy, money, relationships, health, or what the achievement should mean next. Follow the person's lead on privacy before sharing their news or photos with anyone else. The recipient decides whether they want conversation, ordinary company, practical help, professional support, or quiet.