'If everything originates from me why do I have different reactions to different people?' Listener question

I have been reflecting on my reactions in my close relationships. 

I truly believe (I'm actually convinced) that my reactions to a person are a reflection of what's going within me so I am always happy to look at myself and explore that. 

I have been thinking about two romantic relationships. Two different people. Very similar circumstances. Same me. Yet, it was only when with that one person that I had unbelievably strong, visceral painful reactions. For example, I would have trust issues with one but not with the other person. I would go into fear and anxiety when I didn't hear from one but be absolutely fine and at peace when I didn't hear from the other person. I would be scared of being left by one but not the other person, and so on. 

So, I am curious about it. On the one hand, it seems that if my reactions had to do with me, then I should have the same anxiety or trust issues and/or similar reactions in both of these relationships. On the other hand, when I look back, I feel like those reactions to some extent were my wisdom telling me this particular relationship wasn't right (and it wasn't and my trust issues turned out to be valid in the end), and yet, it is also clear to me that these reactions have very much everything to do with me! I'm just curious why they showed up in one and not the other relationship. Would love to hear your thoughts about that.