Why doesn't Pip feel ashamed for stealing Mrs.Joe's food when he does feel guilty for not telling the truth to Joe?

Pip doesn't feel any longing to tell Mrs. Joe. He stole the pie for good reason and Mrs. Joe could do without the pie and the truth. Joe, on the other hand has let Pip love him and Pip does not want to lose his respect,

"But I loved Joe—perhaps for no better reason in those early days than because the dear fellow let me love him—and, as to him, my inner self was not so easily composed. It was much upon my mind (particularly when I first saw him looking about for his file) that I ought to tell Joe the whole truth. Yet I did not, and for the reason that I mistrusted that if I did, he would think me worse than I was. The fear of losing Joe's confidence..." Ch 6