A good friend can disagree with your decision without becoming invested in your failure.

There is a difference between thinking a decision is unwise and hoping it goes badly. A good friend can say clearly that they would not do it, and then genuinely want it to work, and help if it does not. When someone becomes attached to being right, they are no longer on your side of the situation. That difference tends to show later, in how they react to news.

After you go against someone’s advice, notice their tone when things go well. And when a friend ignores yours, decide in advance that you would rather they succeed than that you be vindicated.