What is it with women and arguing?

From a mans perspective a discussion can have 2 outcomes. Either you make a point and the other person agree with you, then you can both feel good about yourself and laugh about how stupid everyone that dont think like you do are.

Or

You disagree, and you can both argue your point til you die from old age, or accept that you disagree.

Women dont work like that. I had a discussion with someone, we can call her Liz. It went something like this.

We were just having a completely normal talk, and somehow got into the subject of beeing married. And for some reason we started to talk about married couple who sleeps in different bedrooms.

Me : it really doesnt make any sense to sleep in separate bedrooms if you are married.
Liz : Well, maybe it makes sense, it can be some medical issue or something.
Me : Still doesnt make any sense, gotta be some hell of a medical issue if you cant even sleep in the same bedroom.
Liz : Well, maybe one of them have cheated on the other.
Me : still dont make sense, if you have cheated and are sleeping in separate bedrooms you might as well just get divorced.

This is how the discussion,that eventually got into an argument, went on for about 30 minutes. Until I finally asked her why she is making excuses for stupid people. To which she replies, "I'm not making up excuses, I totally agree with you". "I was just saying that other people might look at it differently."

wtf! If you agree with me from the very beginning, then why the hell do you feel like arguing with me for 30 minutes over what someone else might think about it all?

Had this conversation been between two men, it would have looked something like this.

Me : Married couple that sleeps in separate bedrooms are just stupid.
Some random made up guy: Yeah, I totally agree with you, they should just get a divorce and get it over with.
Me : Yeah..
Some random made up guy: Yeah..
Me : I guess some people are just stupid and dont make sense huh?
Some random made up guy: Yup, seems like it. Wanna go grab a pizza?
Me : Sure.

Can anyone, anyone at all explain to me whats up with women and their habit of complicating things?