I had a young lad work with me for 3 years. I had known him most of his life, and he had had a succession of jobs which he had lost.
I gave him plenty of chances, but he sadly took advantage of my good nature. By this I meant that I would go miles out of my way to pick him up and drop him off, always gave him the easiest work to do, he was on his phone much of the time, and he was often off sick. It came to a head when, on the first day he was due back from another 3 week sick stint, he told me he had been offered some temporary work with a friend. The work turned out to be unpaid (he didn't tell me this at the time) but I told him that we were calling it a day. This left him with no job, and fewer prospects of getting another. It is a tough world, but I had to do it for my own sanity.
Moral: it's your business. If someone or something is getting in the way of its smooth running and success, change it.
John