I didn't have my father or step father walk me down. I had a friend walk me down that was there for me during divorce and moral support with our work and personal life. I adopted him as my big brother. I asked him if I ever get married again will you walk me down the isle and he did.
I don't see anything wrong with this. I think its sweet that she is singing about how she found the right man. If I was fatherless I would do the same thing, it shows she is strong and that she still believes in love. Plus she is pretty and has a pretty voice so it works.