What do you think of a girl who loves 2 guys at the same time?

Not only is there many better terms, that was about the worse you can put to it. Love is very easily confused with similar emotions, and again it's not degrading if I tell you that you've likely never felt love. It's me telling you that it is rare to find love in it's purest of forms.

Love is what you think it is. Emotion is very amorphous and I don't think you can really define an absolute sensation like that, because what you feel and how you feel it depends so much on other factors.