[LouisaMay]

Please don't avoid them! No. Be direct and honest and friendly. Just as you said here, express that you appreciated their kindness and hospitality. It's an honor for someone to think that you should be in his or her fraternity! Focus on the positives. You don't owe them every nitty-gritty detail of why you are quitting, but be honest that the organization isn't going to work out for you but you would like to continue your friendship. Good luck!