Am I the problem in my relationships?
You are the problem in your relationships if a specific pattern of yours keeps showing up across different people, different fights, and different circumstances, and the common denominator is not bad luck, it is you. That does not make you a bad person. It makes you someone running an old strategy in situations that no longer call for it.
Look for the pattern, not the fight
One bad relationship tells you something about that relationship. Three or four relationships that all end the same way, with the same complaint from the other side, tell you something about you. Maybe every partner eventually says you get distant when things get serious, or every friend eventually says you turn small disagreements into referendums on the whole relationship. The specific accusation matters less than its repetition. If you have heard a version of the same critique from people who never met each other, that is not a coincidence of who you dated, that is data about how you operate under closeness.
Why this makes sense and isn't a character flaw
Whatever you do that hurts your relationships now almost certainly worked for you once. The person who goes quiet during conflict often learned early that talking back made things worse, so silence was armor, not avoidance. The person who needs constant reassurance often learned that attention was inconsistent, so checking in became a way to manage the fear before it managed them. These are not defects, they are adaptations that outlived the situation that built them. You are not broken, you are running a program that was written for a different set of conditions than the one you are in now.
The distinction that actually helps
There is a difference between being the problem and being the only variable you can change. You cannot audit your ex's childhood or your partner's attachment history, you can only audit your own responses, so start there regardless of whose fault the last fight actually was. A useful practice is writing down what you did in the ten minutes after the last three conflicts you had, not what you felt, what you actually did with your hands and your mouth. Did you leave the room. Did you send a long text. Did you go quiet and wait for them to fix it. That list, done honestly, is more diagnostic than any amount of wondering whether you are a good partner in the abstract.
When it genuinely isn't you
Sometimes the honest answer is that you keep choosing people who are not available, not that you are unavailable yourself. If your pattern is picking partners who are married, emotionally checked out, or actively unkind, the recurring element is your picker, which is a real and fixable thing, but it is a different diagnosis than being the problem inside the relationship itself. The tell is whether you behave well once you are in it and simply keep starting from a bad position, versus whether good, available, willing people keep ending up frustrated with you specifically. Those call for different fixes, and conflating them just makes you feel guilty without getting more accurate.
When this runs your life, it usually traces to one underlying pattern. For this, it is most often the Mirror rhythm, the thing under the behavior.