Fantasy...All virgins can make that claim...Has nothing to do with intentions...
After the 'til' happened, Mary could then say, 'I now know a man'...
The point is, it is not a claim -- she is not claiming anything in Luke 1:34. She is simply puzzled that a prediction is made about her having a son. A woman about to be married would not be puzzled at all. She would say something like -- Thanks, so it will be a boy. Unless there was no possibility of conceiving from Joseph at all.
Read the scripture with attention and you will learn the truth that the Catholic Church has taught for centuries.