SM Most people have slight behaviors, but some people have this hobby, which is also a personal preference and not a pervert.
If you are confused about this matter, I suggest you talk to her and have a good talk. It doesn't matter if you don't do anything with mild SM.
If it really doesn't work, I suggest you go to psychological counseling, and you two do it together, because there is a question about her hobbies and your opinion.