A self - fulfilling prophecy? It's where you predict that something will happen and then, because you believe it will happen, you set out, possibly unconsciously, to make it happen. For instance, someone might say to themselves, "I am not lovable, my spouse will leave me because nobody ever stays with me for long".
Because they believe that they are not a lovable person, they act in that way and quite unconsciously drive away the very person they would like to have stay with them.
Another possibility is where someone keeps themselves "poor". They believe that they never have enough money and that they will always be in "want". Even if they win a fortune, their beliefs mean that the money will be "lost" or frittered away and they will be back to where they started - "poor" again.