taighafsXDThis happens to basically every pair of headphones ever, it's caused by the jack getting wear and tear on it to the point where eventually one of the wires inside it either shorts out or disconnects, and it only connects when you hold it at that weird angle.
Are there any good ways to delay/prevent this so the headphones don't die within a few months?
Just don't be rough with the ends of your cords, and don't bend them on sharp angles.