Something they did, or said, perhaps an ongoing behaviour, or a u-turn on a mutual agreement, has caused tension to brew between the two of you, and your immediate reaction/response is defensive because you take their actions personally.
But, here's the thing...
Reflect on when and how you met that person. What were your circumstances at the time and what was the situation that led to you meeting each other? During the course of the friendship, were things always 50/50 or did you pour in more? How often were you there for each other? Are you realising that the friendship was one-sided, or have you concluded that (due to what you or they were going through when you met) one of you needed what the other was bringing and now you've outgrown the friendship? Even if what you have done to your friend, or what they did to you, is wrong, maybe it will serve you both to simply think about and acknowledge the lessons to be learned and then move forward without any conflict. Arguments bring chaos, things said that we often then regret, headaches, insecurities and more arguments!
"Life is short"—how many times have we heard or said that? Let it be your reminder to show your friend (and yourself) a little empathy. Afford them some grace, allow yourselves the space to process things so you can move on from the upset in a positive way and let go if that’s what feels right.
Regardless, be of the mindset that empathy is important and it starts with you.