Sweetheart, your friend is clearly mistaken. Kristen just confirmed her relationship with Robert Beautiful Pattinson. Taylor just got out of a relationship with Lilly Collins. There is no Kristen&Taylor. She has said a billion times that their like siblings. And Taylor is 19 , I don't think he would be getting married in his most memorable years of life.
Kristen&Robert on the other hand have been dating since New Moon Promotion tour. Its quite obvious. So Your friend is highly mistaken and some people who spread rumors like this , don't do research before talking.