A conversation becomes harder to begin when it carries every unresolved frustration at once. Choose the specific issue that requires an agreement now.
Describe a recent observable event, its effect and the change you need to discuss. Avoid building a long case from remembered motives. If the situation involves serious misconduct or personal safety, use appropriate support and formal channels rather than treating a conversational technique as sufficient.
Prepare the request
A fictional example: when the handover arrived without the open actions, I had to reconstruct them before allocating work; can we agree which fields must be complete before transfer? That gives both people a practical point to address.
Ask for their understanding of what happened. You may discover an unclear responsibility or a requirement that cannot be met with the current arrangement. Listen before deciding the remedy.
Leave with a checkable agreement
State who will do what, by when and how the change will be reviewed. If no agreement is possible, record the unresolved decision and the appropriate next route.
You do not need to settle the entire relationship in one meeting. A smaller honest conversation can resolve one important pattern and show whether future discussions can be handled constructively. Keep the scope clear enough that progress is possible.