First ...good job for jumping in. And second...your story isn't riddled with unethical choices and bad decisions that typically get the hardliners on there soap boxes so I don't think you have anything to worry about.
How did your relationship start with this girl? Where you actively poly at the time.
How old are you both? Do you live together? how much time do you dedicate to each other? How is your time with your other Gf's decided? How is her time with other the other men decided?