Blame and defending will never lead to resolution of conflicts. People on the defensive take in very little information. We grow up learning to deny and defend. Common parental messages begin with the words, "you need to" ; "you didn't" ; "you should have". We grow up learning to deny and defend.
I have one brother and while we were growing up he constantly got in trouble. As a result he got blamed for things he didn't do. Denial became his first response whether guilty or not. I was the good girl and never lied.
I had a book, "The Little Red Hen" which I loved. One day I had a safety pin in my hand while reading the book. I scratched the letters of the title on the cover. A few days later my mother, who taught us to always take good care of our things, noticed the artistic enhancement on my book.
"Who scratched this book?" she asked in a tone that scared me. "Did you, Elva?" "No," I answered immediately, instantly terrified that I would go to Hell for lying. My mother turned toward my brother. He answered with an emphatic, "no!" She continued, "Don't lie, Edward." "I didn't do it," he repeated. To my horror he got spanked for lying. I was doomed to six months of terrible guilt and fear. When I could stand it no longer, I tearfully confessed.
You can understand why my brother grew up skilled at being defensive. One of the first skills learned in communication is "do not blame, do not defend". Thus, the rule, use "I" instead of "you". When you own the problem it becomes much easier for your partner to listen and not defend. He/she may not completely trust you, but inch by inch you learn it is worth taking a chance.
It may be unrealistic to use this incident as an example, but let's go there. My Mom might have said, "I have a problem with books being damaged and I am wondering how this book got scratched." I think I could have had the courage to tell my mother I didn't mean to damage the book. I just wasn't thinking." She never would have spanked me, and I would have prevented weeks of sleepless nights and nightmares about going to Hell. The lesson here is you will be far more likely to solve a conflict if you start with "I have a problem with......."