I was sitting in a cafe with a friend who expressed an interest in me coaching him. I told him I would, but he needed to understand that while I value his friendship being his coach was a different matter. As a coach there is absolute secrecy in what is said between my clients and me, but just as importantly, he needed to understand that to do my job effectively I sometimes need to ask questions that might make him feel uncomfortable, in fact sometimes some of my questions make me feel uncomfortable just for asking them.
I told him that it's the same thing with all of my clients. While I enjoy having fun in my client sessions when appropriate, there needs to be boundaries set up because, while friends are great cheerleaders, (as are coaches), friends usually tell you what you want to hear, not what you need to hear. To be effective a coach often needs to probe for the deep truths clients never tell anyone, especially themselves. If they did admit it to themselves they probably wouldn't feel stuck and wouldn't want a coach to help them.
That's why if you feel the need to have someone help you with a problem don't go to a friend for help. It's useful if you want instant relief for something, and frankly most of us do from time to time, but the relief you feel will be short-term and it won't fix the issue. A great coach who is doing their job will as necessary probe deeply and sometimes uncomfortably to help reveal those hidden truths and that's what helps bring about those moments of transformation that change peoples' lives.