This city would drive anyone to it. Seriously. I think that cohabitation pre (or instead of ) marriage is less an effect of declining morals (I saw a study not so long ago that said that the percent of people having premarital sex hasn't changed since 1920 or so), and more a conflation of several other factors:
-People get married later
-More people are going to college, and therefore live away from home from the time they are 19
-Not so many of those people want to move back in with their parents until they get married (later)
-It is expensive to live in NYC
-Living two people to one bedroom is cheaper than any other reasonable alternative (as Orthodox Jews in Washington Heights, and some parts of the UWS can tell you)
-Most people don't want a same-sex roommate, unless they swing that way
CJ and I had a conversation on this topic over the phone yesterday.
Me: The roommate and I haven't found an apartment yet.
CJ: Sorry sweetie.
Me: Yeah, it sucks. I tried to convince her that we should share a room, there is a beautiful apartment near us for $2600/month. In an elevator building. With a laundry room. Except that it would suck to split it. There's enough room technically, but it would leave us with a weird long, thin space.
CJ: Too bad that you don't have a boyfriend that you can move in with.
Me: I know, maybe I should go find one.
CJ: The roommate probably wouldn't like that.