What is the biggest sin?

Hello.
What is the biggest sin from your opinion that woman can have? For every person there is list of the biggest repulsive things that will stop a person from dating with someone. It could be falsehood, arrogance, rudeness or greed. It depends from person. As for me, I hate lies. I prefer to hear the truth that could be very awful than sweetest lie.
How many times do you refuse to a woman because you noticed a certain sin in her? When people are in love they are like blind. Don’t see anything bad and in contrary they see only good and positive sides of person they are interested in.
Would you date a girl who is perfect in all ways but has sin that you hate? What is important for you? To build relationship people need to have compromises. But how long relationship will lasts if someone has a sin you can not stand?
I think it is one of the important topics people need to discuss to find out if they are right for each other. Don’t you think?
Veronika