Here's why:

* Newton's Law of Universal Gravitation: This law states that the force of gravity between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

* Inverse Square Law: The "inversely proportional to the square of the distance" part is crucial. This means that if you double the distance, the force becomes 1/2² = 1/4 as strong.

In summary:

* Distance increases: Gravitational force decreases.

* Distance decreases: Gravitational force increases.

* The relationship is not linear, but rather an inverse square relationship.