Why am I nervous around my girlfriend?

Could be multiple things. Perhaps she excites you so much, perhaps you're a bit insecure, perhaps it's something you're afraid to do or say. It's a very diverse question.

It seems like you really like her. There is nothing wrong about liking someone a lot, Stay with her. Talk.

bcoiz.. i dont knw whether my parents will accept her.. and may be wat others will feel .. they may understand me as a ill mannered guy

You love her and might be scared of losing her. It could be your anxiety just giving you "What if?" thoughts.

Feeling nervous around people can be a normal feeling. Tell me more about your relationship. How long have you been together?

Maybe you aren't completely open to her? Maybe you feel like she's the better half of the relationship, or whatever it is, it's something you need to address together.

It could be a number of things. Is she your first girlfriend? We tend to be nervous around people we've developed a new relationship with. You should realize she's your girlfriend for a reason - she obviously is interested in you. There's no reason to be nervous :)

I noticed when I first started seeing my boyfriend, I was super nervous around him. This went on even after seeing him for over a month! I realized that I was so nervous because I liked him so much! I was afraid of making a fool of myself and messing things up, but then I talked to him about it. He said he was nervous too! I say that once you find the source of why *you* are nervous, talk to your girlfriend about it. As soon as I talked to my boyfriend, my nervousness went away.

Maybe you two just got together. Maybe you are not comfortable around her yet. Maybe the two of you haven't really connected enough for you two to truly be yourselves. That is okay. You just have to talk to each other. It'll take time, but it will develop into something better.

You are probably nervous because you want to be the best boyfriend you can be and sometimes that makes you nervous.