There are two different kinds of primary relationships in the game.
The first type of relationship is any that Niko has with various females he encounters.
Most games in the series are set in fictional locales modelled on cities, usually either Liberty City, Vice City or San Andreas, which are stand-ins for New York City, Miami and the state of California, respectively.
You're going to have to go to an internet café and browse the in-game websites Love Meet and Craplist (which are always on your homepage when you logon).
This is a list of in-game websites accessible on the Internet in Grand Theft Auto IV, The Lost and Damned, and The Ballad of Gay Tony.
These are not real websites but most of the domains are owned by Rockstar Games and redirects to the official GTA IV website in real life.
The Wikipedia links in brackets refer to the real life websites it is believed the game's websites parody. The game's traditional news websites (discounting LCPD's website and the secret blog) change as the story progresses, many of their news articles documenting missions Niko does in the game and providing backstory or aftermath to those missions.
The first game encompassed three fictional cities, while subsequent titles tend to emphasise a single setting.
Gameplay focuses on an open world where the player can choose missions to progress an overall story, as well as engaging in side activities, all consisting of action-adventure, driving, third-person shooting, occasional role-playing, stealth and racing elements.
However, that shouldn't daunt you from building as many relationships as you can, because they happen to provide some of the deeper and more rewarding experiences Grand Theft Auto IV has to offer.
In fact, without building up relationships with myriad characters in the game, you're going to miss out on a lot of what the game intends for you to see.
Tip: On the Playstation 3 you can type in web-adresses by connecting an USB-keyboard at your PS3.
Website where they raise money to get radio presenter James Pedeaston (known of The Wild Traveler in GTA San Andreas) liberated out of prison in Bali.