I would agree with Lexie on this one. While communication is all well and good, seeking reassurance is indeed putting a burden on the other person to make you feel better. You also put her in an uncomfortable spot, asking her for an explanation she might not want to give, which could lead to some resentment on her part. I could see that going badly. You could put pressure on an already strained relationship.
That said, I struggle with this too. I constantly want reassurance. I always tried to get it from my soon to be ex. In that relationship though, he was always so emotionally distant even when things were good, and he usually was mad at me. But that's a different situation. You have become aware of this tendency in yourself. Al anon says its awareness, acceptance, action. So maybe just work on accepting these insecurities and then you can work on the action part? That's what I am trying to do for myself. Just some thoughts. You have to do what you think is best for you.