The hardest part of helping someone who's struggling is that they often don't look like they're struggling. You saw something. Trust that.
If you're worried about someone's immediate safety, call 988 together or help them reach out.
You don't need to fix it. You don't need to know the right thing to say. The most powerful thing you can do is say, simply: I've noticed you seem like you're carrying something. I'm here. That's it. That's the whole conversation.
Avoid minimizing, "everyone feels that way" or "you have so much to be grateful for" can make someone feel more alone. Don't push for details they're not ready to share. Don't promise to keep secrets if you're genuinely worried about their safety.
If someone tells you they're thinking about hurting themselves, take it seriously. Stay with them if you can. Help them call 988 or get to a safe place. You don't have to handle this alone either.
The research is clear: social connection is one of the most powerful protective factors against mental health crisis. You being present, paying attention, and saying something is not a small thing. It may be the thing.