It's normal. There is a crack in the nipple. As long as there is no pain and no impact on life, there is no problem. If you don't feel good, it is recommended to do local plastic surgery. There is a case: Wow, when I was a child, my hands were really flat, so I buckled them, but it didn't hurt, so I buckled a small piece of dark color. Later, when my nipples grew up, there was an obvious ditch. I don't know if your girlfriend is the same. I gave birth to a doll last year, and I was afraid that it would leak when feeding. As a result, it didn't affect it at all, except that the shape on the right was not so regular and spherical, and it was slightly flat. That seam is gone at all. Ha ha. If I have a daughter, I will definitely tell her not to buckle her nipples, and don't buckle the skin under the fingernails, which makes the fingertips less beautiful. It's all caused by childhood.