Some so-called liberals worrying over a simple question.
Problem is you are perhaps living in any Islamic country, while your conclusions regarding Western society are wrong.
On topic, I strongly disagree on 2 people living together without getting married.
The consent to live together (even for a shorter period) is a marriage itself. I know you cannot understand it at moment. But wait.
Basically, you are hiding behind the excuse of "knowing her better", only to spend several years with her, having kids with her,
NO.
Firstly, in present day western society, people don't hasten in making kids, but they take their full time. Therefore, they go for kids only after mutually agreeing with each other.
Secondly, even if "unexpected" pregnancy occurs, then today they have the full right to go for abortion.
and eventually leaving her as a single mother because "she was not my type".
You are totally wrong about this "leaving" issue.
In West, if you have children, then you are FULLY responsible even after you have left the wife.
You cannot leave her as "single mother", but state makes you equally responsible to take care of the children as so called (in your language) "single father".
Either you have to pay for the kids and have them on the weekend and holidays, or new rules are "joint sharing custody" where one week child stays with mother and one week by father.
Therefore, no one could run away from the responsibility and women are not "single mothers" in the West.
This crap leads to children not having their father's name throughout their lives and exposes the cowardice and fear of responsibility of a lot of men, who are ready to have fun, but will be the first ones to run away like cowards at the first sign of responsibility.
Again wrong.
Women have complete choice at their disposal. If they have become pregnant and don't know the partner, then they could simple abort it.
But if they still want to have a child, then they are fully supported by the society. None will call their children as "********" or "illegitimate" (While Islamic Sharia does do a wrong thing to the innocent children by labelling them as illegitimate (Arabic: Walad-ul-Haram).
Again, even if a man is coward and don't want to take a responsibility, but this is not going to help him and he has to take the responsibility.
Please also remember, only religious (christian) families are having children, while they believe abortion is against their religion. As far as non-religious women are concerned, then they are not having any unwanted children as they go for the abortion.