I would say that Pip's relationship with Joe has three stages.
At the start of the book, Joe is Pip's master, officially, but also his fellow-sufferer because both of them are dominated by Mrs. Joe.
For most of the middle of the book, Pip is ashamed of Joe. Pip has his "great expectations" and he is ashamed to be connected to someone who is a common laborer.
By the end of the book, Pip has come to his senses. He has realized that there is no shame in being a common blacksmith. So now he is proud of Joe and happy to be connected to a decent man like Joe.
At the beginning of the novel, Pip is a boy of about 10, and Joe, his brother-in-law was nearly 30. It seems as if the two are appropriately matched as "ever the best of friends" because Pip has had to grow fast, and Joe is simple-minded needing a buddy.
As Pip ages and grows his expectations after time at Miss Havisham's and finding he gets to go to London to become something great, he leaves Joe in the dust. Pip thinks he is too good for Joe and looks at the life of the forge as disdainful.
By the time we reach the end of the story, Pip feels great sorrow for how he has hurt Joe, and Joe is ready to forgive as well and their relationship is repaired.
While Pip's relationship and view of Joe's friendship does, indeed, undergo changes as Pip's values alter, from Joe's perspective, there is absolutely no alteration in feelings or attitude toward Pip. Even while Pip is a child, Joe has respect for Pip, complimenting him on being an "oncommon scholar." He protects and cares for Pip at every turn. When Pip bemoans being "common" and having coarse hands and boots, Joe explains that Pip is not at all common in his heart. Then, when Pip is embarrassed by Joe on his London visit and neglects to visit when he is near the forge, Joe's love is constant. Rushing to aid the burned Pip, who expresses his guilt--"Tell me of my ingratitude"--this friend replies,
"Which dear old Pip, old chap,...you and me was ever friends. And when you're well enough to go out for a ride--what larks!"
Constant in his friendship for Pip, Joe's words of love echo like a refrain through the entirety of Great Expectations by Charles Dickens.