Let me tell you it is the one thing I can't tolerate from my boyfriend. He constantly takes over my converstaions, and if I am telling a story, he will just tell the ending, before I even get started...and if he's had a beer, well there's just no stopping him!!
If I am on the phone, he will constantly talk and want me to ask them questions, when 99% of the time they are already telling me what I need to know! At least I have the good manners to write it on a piece of paper....
No, I would have to say that surely this is just a personality thing......