For some reason this phrase popped in my mind and I looked it up in google to see what would come up. I found this: http://www.phrases.org.uk/meanings/60500.html . Here it says that it was first adopted as a feminist slogan. I doubt today that feminists still support this slogan.
Relating this to heroes and heroines in comic books: It never really seems this way for heroes and heroines. Heroes and heroines usually handle their problems by their own. They, most of the time, do have weaknesses to certain people but they are usually not getting help from them. It usually ends up with the hero or heroine helping his or her love. We don't really see the beloved somehow standing behind our hero or heroines and supporting him/her.
For example, Clark Kent, loves Lois Lane but he is not Superman because she is "behind" her. She doesn't necassarily help Superman in doing what he does. She is a motivation for Superman, but I haven't witnessed her openly motivate him or tell him something which made Superman a better at what he does.
I think the same is also true for Wonder Woman and Agent Tresser. She is Wonder Woman on her own. She indeed does have a weakness for him but I don't think that he is a force supporting Wonder Woman in what she does.
I don't think neither Superman would be less of a Superhero without Lois nor Wonder Woman less of a Super Heroine without Tresser.
Like I stated I don't have the best background in comic books but what I've seen so far is that this quote is not valid for heroes and heroines.