Re: Are pairs really made in heaven?
Well the time of your birth, death and the family you would be marrying into are predecided. But ‘dua’ can change destiny. we know that as well 
Allah knows everything but he too has given us the power to do things the way we want. It indeed is a paradox our minds might not be able to interpret.
And as for bad men being for bad women and vice versa. That too holds true. But let’s take it this way.
Not every ‘good’ man/woman is flawless or an angel. Neither a bad person is born evil. Even Iblees was once amongs Allah’s obedient. Maybe they were really bad sometime in their life before. and may be the person they marry is a total jerk ..and maybe this is a temporary testing time and that person eventually becomes good later on. And maybe this is the reason we need to ask for keeping us on Siraat-e-mustaqeem (the right path) Ayat of Surah Fatiha that we recite in every Namaz !
See this is very very intricate - but if you do think about it, it makes sense. We can’t judge a person’s piety or being evil on his current behavior…people transform their circumstances change .. maybe the
good are for good is judged over a period of time - maybe the whole life. There is always room for forgiveness for us by Allah !