Well there's metaphor and there's literal truth. As a metaphor, Wonder Woman's story works because she's going against authority to go after who and what she loves. You don't need to be literally the same as Wonder Woman to apply the metaphor to yourself. Queer folk sometimes have to defy their parents to love someone they are not supposed to love.

If you want everything to work on a literal level, then I guess Wonder Woman has to be literally gay and she can't love both men and women. I think Wonder Woman is more like Miranda in Shakespeare's THE TEMPEST, when upon seeing men from the outside world for the first time, she exclaims, "O, brave new world that has such people in it." Steve represents for Diana what Ferdinand represents for Miranda--another world she has never known and that by nature she needs to know and experience.