Generally, if a woman you've been intimate with, who acts like your girlfriend, consistently avoids introducing you to her social circle or friends, there are usually three possible reasons.
The first is that she sees you as a backup, just playing around. This is the most common and familiar scenario.
Second, she likes you but doesn't fully trust you yet, so she's decided to wait and see. She isn't looking for anyone else; she just wants to observe you a bit longer. If you get past this stage, it generally means you're heading towards marriage.
