I'm a bit late to the party, but yes, goldfish do get lonely. After having kept two goldfish in my 55 gal for 7 years, one of them passed suddenly. The other languished for a few days and then died, too. He seemed to be frantically searching for his lost buddy until his last minute. When I acquired another goldfish (single goldfish in a 55 gal) he remained by a tiny mirror I'd placed on the side of the tank because he thought it was another goldfish. He only stopped this and "came out of his shell" when I added another goldfish to the tank. Now they are best buddies.
So while goldfish will be a good fishy buddy for you, they have fishy social needs (unlike betta) that do need to be fulfilled. But having other goldfish in the tank doesn't make them interact less with you. You get a whole swarm of fish greeting you instead of just one.