gurfateh,
Well i'm new to this site & the very first view of mine to this post made me very seriously think about your problem.
after reading all the replys to your post and finding people in general have same impression that your mate should accept his sister back to sikhi.
but i think most important question here would be is she ready and metally prepared and most importantly willing to accept sikhi.
we simply cant force any faith on some one. all we can do is that make other person reallise with our good deeds that this could the options she can think of following, of which i think would be not to resist her coming back.
well this is general problem and can happen to anyone. so to accept "his hukam" is best way to calm ones mind of what has happened and is happening, make this realise to ur mate.
surely its difficult to digest the past when it resurfaces, but again "his hukam" philosophy does wonders.
Well on topic of difference between what girls do & what boys do, its senseless debate which never ends. only thing i think anything done good or bad equally applies to both the genders without any bias.
i'm no one to preach, please dont mind if i had been wrong at any place.
all will be well.
