Before you meet. Keep it future-focused . Even though a past or ongoing event disturbs you, finding fault and blaming is usually unproductive.
People often respond defensively when they think they are being attacked.
If you think about how you would like things to change, you are more likely to receive a positive response. Express your concerns rather than your solutions. Before you meet with the other person, think of a way to state your concern in a non-threatening way. If the concern is stated generally, rather than specifically, it is likely to be less threatening. Express your needs.