“Honestly, I was jealous” fixes more friendships than a hundred reasons why you were annoyed.

Annoyance is the respectable cover for envy, and it comes with reasons: they were showing off, they went on about it, they changed. Those reasons let you be cross without admitting that you wanted the thing. Your friend can feel the real shape of it anyway, which is why the list never clears the air. Saying the plain word ends the argument because there is nothing left to defend.

If a friendship has gone cool since something good happened to them, try the one sentence. It is embarrassing for four seconds. Most people meet it with relief, and some will say they felt it too when things went your way.