Roles in a modern relationship

The world has significantly changed today from what it was even 50 years ago. With the appearance of modern technologies, that make our lives easier and funnier, our attention has shifted from the traditional model of a relationship to totally different values.

What are those values in the modern world, if we speak about a relationship between a man and a woman? What people are looking for today? In many countries of the Western part of the planet people don't see any sense anymore in getting officially married. Many of them don't want to get involved even in a serious relationship, preferring "drifting" from one to another. Some of them explain this by the equality of rights and desire for freedom. There are others, who rather call it a lack of responsibility and immaturity.

So the question is, do we still need the traditional model of a relationship? What is the modern version of it? What are the responsibilities of both in it, if there are any? What is the distribution of roles?