Your exes were awful. You’re a bad judge of character.
Just like us, men have a learning curve in their relationships. With time, each girlfriend gets better. That means, if you go back in time, each ex gets worse and the more you know about them, the more you think, “Is my boyfriend an idiot? How did he date her?” But, if you looked back in your dating history, there are some exes that could be evidence that you’re an “idiot” too. But you’re not. You both have just done your learning.