@onkar22,
Is she not allowed to have friends?
I am not saying that she should prefer them over you, but you need to understand that people in relationships have, well,
other relationships. And those are also important. Making her feel that she needs to choose is an enormous mistake - if you do that, I can just about guarantee that she will select her friends over you.
So, what to do?
Come along if it makes sense, or give her your blessing to hang out if it's not. Use that time for yourself - you do have other friends, do you not? Then spend time with them, or do other, constructive things, like work or schoolwork or exercise or cleaning or whatever you need to do/floats your boat.
Couples do not have to be together 24/7 in order to stay together. And, truth be told, it's a lot better for the overall long-term health of a relationship for you to
not be together constantly.