To paraphrase: the Fermi Paradox asks that if extraterrestrial life is common in the universe, why can they not be observed yet? The explanation (that I think is the best) is that distances are too far away for civilizations to communicate or meet.
I think this is a good explanation of this paradox because there is an ultimate speed limit for everything in the universe (light, energy, matter, information, etc.) and anything traveling at this speed would still take a long time to move from star to star. Sure, there could be wormholes and Alcubierre Drives might bypass these distances but I'd assume a civilization would be far advanced to use such methods, assuming they exist...because of the energy and science necessary for such phenomena, such civilizations might be indeed a rare occurrence and few and far between.