A real friend screenshots your good news and sends it to their mom.

Being glad for someone in private is one thing; carrying their news around and telling other people is another. It means your success registered as genuinely good rather than as a comparison, and that they think of you as belonging to their life, not just their week. Nobody does that out of politeness.

Notice who repeats your good news to people who have never met you. Be that person too, and say the good thing about a friend to someone else, whether or not it gets back to them. Praise given behind someone’s back is worth more than praise given to their face.