How does one leave one collaborative group for another, prior to the start of the research? This relates to switching project teams for graduate course work, switching research labs, or basically dropping any collaboration. How does one do so politely?
My specific situation:
I have been asked today by one of the best teams to join their group for our major University project. However, I have promised my friend 2 months ago that I will join his team.
How can I join the better team without jeopardizing my relationship with my friend?