Wow this is more common than I thought! When H and I first separated I had to send him an official email about the house and at the time I was so d@mn mad at him that I signed off the email with my full name so when H replied he also used my full name. We went backwards and forwards in this formal way until eventually he got fed up and reverted back to addressing me by my nickname and had never gone back to using my full name. Very strange indeed!!
