If you were dreaming of living alone on deserted island, it can mean that in your waking reality, you were abandoned to handle your situation by yourself. You have to cope with the harsh environment, and fend for yourself. Besides defending yourself against attacks from the natural elements, you may also have to fight against your enemies.
In waking reality, you might be in a lonely position, where other people are not allowing you into their loop. You’re simply not a member of their inner circle, for reasons best known to them. This type of situation might trigger your brain to create the dream about living alone on a deserted island.
In reality, if you hold principles that do not agree with the masses, then you are alone on your deserted island. Additionally, you may face being cut off for being the black sheep of the group of humans.