What should be done if a friend is suicidal but doesn't want to tell a
Tell the friend you understand and you would never betray his o
Ask the friend why he or she wants to keep it a secret.
Tell the friend they can't keep a secret about something so seriou
Ask the friend to think about the repercussions of keeping it sech

Ask the friend to think about the repercussions of keeping it secret.

Explanation:

When someone remains silent about their intrusive thoughts or excruciating behavior towards them-self, it is a very serious topic as the person may be on the brink of playing into the thoughts. There are reasons behind why the others are wrongful acts.

"Tell the friend you understand and you would never betray him."

This is simply the worst option to choose because it is not helping your friend nor it is helping yourself. You're allowing your friend to continue to hide their emotional pain which could possibly lead to a dead end.

"Ask the friend why he or she wants to keep it a secret."

As this is a semi-acceptable answer, it just isn't what you should do at the time being. See, it allows your friend to talk about why they're so secretive about it, but it doesn't do any good. As many of us want to help our friends through their tough times, this friend is at a point where there needs to be some sort of action.

"Tell the friend they can't keep a secret about something so serious."

This is a bad tactic to helping your friend. You are both losing their trust and you're allowing the friend to try to figure out how to get around the situation. The friend could go and act on their intrusive thoughts then and there to avoid confrontation. As hard as it is to hear that a friend is going through this, you have be somewhat reasonable in your decisions.