George does rely on Lennie. Lennie enjoys hearing George's dream of how they will one day own a farm together. If George did not have Lennie, he would have no one in which to share his dream. What good is a dream if one has no one with which to share it?George does get frustrated with Lennie, but George needs Lennie as much as Lennie needs George.
It is so wonderful to be needed. It is satisfying knowing that someone depends upon you. Having no one to depend upon you leaves you feeling lost and unnecessary.
George too needs Lennie for comfort and company. George mentions often how lonely some of the other ranch hands are. He mentions that they have no one:
Guys like us, that work on ranches, are the loneliest guys in the world. They got no family. They don't belong no place.
But with Lennie and George it is different. They have each other. They need each other. They share a dream together. George is comforted in having Lennie as his companion.
One of the most difficult things George has to do is shoot his companion Lennie. Immediately after shooting Lennie, he calls off the dream. Even Candy realizes that the dream is over once Candy learns what Lennie has done. The dream of having a farm depended upon Lennie. It was Lennie who wanted rabbits on their own farm. It was Lennie who kept asking George to share the dream. Lennie loved hearing the dream over and over. George enjoyed telling the dream over and over as long as he had Lennie to tell it to.
Lennie and George were like family.