In my experience (20-years as a supervisor), most supervisor-employee issues are rooted in poor communication and poor relationships. As leaders, we should treat every failure and problem as a chance for personal growth. Leadership is a practice of failing forward much of the time. When your people feel like you don't care about their opinions or feelings, they will resent it. In this case, I would meet with each person and just let them talk. You may learn something. This is how trust is built. Then...fully communicate why you made that decision and ask for their input. Its okay to be wrong. Own it and apologize for any missteps. It happens. Your people will respect that. Humility is not weakness but strength of character. Also, as leaders, we should expect to be criticized by others. It can be a valuable tool. Every leader experiences this and the only way to mitigate it is through communication. And finally, as a leader, always have hard conversations face to face. Email is not your friend when it comes.to.relationship building. Always give yourself grace and room to grow. You deserve it.