Did she think all that “pomp-n-circumstance” was going to follow her, when SHE is the one who chose to leave the royal clan (and their history/heritage of service)? What did she expect? You can’t have a happy, life-long relationship/marriage unless two people GENIUINLY are in love and ENJOY being with one another...every day, week, month, year, always. If that is missing, the relationship is mostly likely doomed...IMHO, of course.
I don't think she (or Harry) realized just how far out of the limelight they would be shoved by taking this move. They probably did not realize that they would become so toxic to other celebrities - who wanted to stay in the good graces of the royals.