It's this male idea that a woman has to man up in order to be taken seriously in the world of men--she has to sacrifice something of what makes her female (maternal love, beauty, sexual fullfillment, romantic love) to take on the masculine attribute of strength. As if strength belongs to men and women can only share in it through some Faustian bargain. That's not true but it's what a lot of people think. In Cameron's mind, he's creating strong women, but he's locked in that thinking that women have to give up something that makes them female to obtain male power.
The truth is, male or female, we all sacrifice parts of ourselves in the pursuit of our goals--and Diana makes those sacrifices--but it's not a gender thing.