At some point all the fun stuff from a new relationship dies down and most of it just turns into a drag. The deepest conversations you'll have are about what to eat or whether you'll be home at a regular time.

I know this is not the case in all marriages but most of them that end in divorce are merely because it started as something fun, marriage seemed the next logical step and then you're sort of locked into it, longing back to the excitement of getting to know each other. Being single is pretty much like that unless you never meet new people you have a fun couple of weeks with before never seeing each other again.