There's more to dating a royal than wearing fancy clothes and tiaras. Royal women are under an incredible amount of scrutiny and any minor slipup (like having your skirt blow up) is seen as having a damaging effect on the monarchy. In addition, Harry's wife would likely be expected to hold a royal role — meaning lots of time spent attending sometimes boring charity events, never being allowed to be left alone due to the security threat, and having your entire public persona dictated by royal secretaries and courtiers. Harry's future bride would be more than a trophy wife, she would be a symbol of the monarchy and would be expected to uphold that image.
Yes, this may sound easy, but this is actually the hardest point for Harry's ladies to adapt to. It's rumored that both Chelsy and Cressida broke things off with Harry because they didn't want to take on royal life.