You don't really know who she is when Chandra asks you for help. Also, depending on how you play that subway scene with Chandra you may not even know she wants you to rescue a friend of hers at all. She's trying to drag you away when you should go home and prepare your little operation so I guess if you're not very fond of her you can easily dismiss her and never know a thing about Abby. Also, this *MC knack of fucking every women he meets* it's just your gameplay, you can have a perfectly virginal route so far