There are situations where some refuse to understand the success of a project where a project manager must be firm has nothing to do with any relationship outside the project. Saving Changes...
In cases where I've had friends of mine as team members on my projects, I've usually met with them 1:1 to make it clear to them that I will be treating all team members fairly and equally and not to expect that our friendship would make me treat them differently.
I use the analogy of the old Warner Bros. cartoon with Ralph Wolf and Sam Sheepdog where the two are fighting one another throughout the day at work, but when the work day is over they go back to being friends.