Often we expect too much from a partner when we ourselves haven't yet mastered these values. Frequently people think, when I find the "right" partner then I will be this way or that. How many people say they want trust in their relationship, yet the second, their partner does something that seems suspicious, they go through their partner's phone, look for evidence of cheating, or scream accusations at their partner?
When a girl experiences their partner even looking at another female, it can be a great punch to the gut. I have been with my partner for five years, and yes, he does make the occasional comment about another girl he has seen. The only thing is that now, I am more likely to say 'yeah, she's attractive'.