Contrary to your previous assertion that examining all aspects of both your and her behavior is unnecessary your subsequent statement below seems to be doing precisely that, which creates a conflict with your initial suggestion.
"There are times when you know that whatever the history between you and a friend has been and whatever has brought you both to this place (who has done what to whom), you know the friendship is pulling you down. "

You make a good point on drawing boundaries. But you cannot do it with bias one sided reflection.

Why is self-reflection important in addressing relationship problems instead of blaming others?

Reflection is a valuable practice that enables individuals to introspectively examine their personal behaviors, communication styles, and emotional responses exhibited towards others. By reflecting on interactions and relationships, one can implement positive changes, fostering healthier and more fulfilling connections. Alternatively, this introspection can facilitate the termination of relationships in a more constructive manner, devoid of unilateral blame.