In 3d the magnetic field from a magnet decreases at approximately the distance cubed rather than with the square of the distance because the magnetic charges from the two poles tend to cancel each other out. This gives me an idea for 2d Gravity. If in 2d an object had a positive charge on the outside and a negative charge inside then the charge of the object would decrease at approximately the square of the distance.
My idea is for each fundamental particle to have positive inertial mass but for some fundamental particles to have positive gravitational mass while others have negative gravitational mass. The fundamental particles would be arranged in constituent particles that would be made of some particles that have negative gravitational mass and some that have negative gravitational mass. The particles with positive gravitational mass would be on the outside of their constituent particles while the particles with negative gravitational mass would be on the inside of their constituent particles. Because the particles with positive gravitational mass would be on the outside of their constituent particles they would also be closer to other constituent particles than the ones with negative gravitational mass and so the gravitational attraction between constituent particles would be slightly greater than the gravitational attraction between constituent particles. This would cause the gravity between two masses to decrease with approximately the square of the distance in 2d and the greater the distance the closer the gravity would be to decreasing with the square of the distance.