In business we work with people that we have mutual interests with. Sometimes friendships are developed during this process. Heck, it can be inevitable at times. Your creative colleagues are sometimes the only folks who you could watch a documentary on Helvetica (yes, the font). We can be nerds with these folks and they really get it or add it to it. You may even have a friend that was your 1st client and continues to support you through your process. Support i.e. embarking on business ventures together and hiring you for personal projects.
Just because we’re friends, you don’t have a pass to be late for a job. Or to forget about an appointment. Or to jeopardize your clients for the sake of a project with your friend. Or to assume that I will work with you on a project when I said “maybe”.