When a boy fools around, goes around and then makes his way back into his community, he still has good chances to be considered an amazing boy. Sometimes even more so due to his journey and "experiences" by a twist of - "look at him today, after all what he's been through, he is a good serious boy..."
However, us girls do not get a free pass to hell and back.
If we fool around, we are forever to be tainted and preceded by our reputation. Girls are not forgiven, and nowadays, I think it's a pretty much accepted concept across the orthodox communities regardless of how fair or unfair it might be.
This principle might be associated with the teachings of our societies allowing a bigger leeway to male stupidity due to their nature and their uncontrollable impulse. G-d forbid a girl should slip and stain that pure soul of hers. It's all beautiful, white and romantic but at times cruel and unfair.
I was inspired to vent about this because I tried introducing a not so innocent but repented girl to a not so innocent and somewhat repented guy too. He refused to meet her on the grounds of her past (going back 5 or 6 years ago, when she was still in high-school). I understand his reluctance and discomfort about meeting her but I do blame society and it's system more than the actual pretext.
G-d judges "באשר הוא שם".
Perhaps it is one of His numerous qualities we should aim to acquire.