Proselytiser said:
Keep yourself sharp don't stop talking to women because you have a girlfriend
This.
And you are perfectly normal. A male of your age has a deep instinct to be seen by as many females as possible, its just part of your genetic programming so don't fight it. Also, you can stay faithful and still flirt. In fact your relationship will benefit from it because
> She will know that she has to be on her best behavior to keep you faithful
> Your sexual appetite will get warmed up from random hotties and you will have more "fuel" to pound that ass with
> You stay on top of your game, because you never know how this relationship will pan out.
I'd take this even further and start amassing a collection of girlfriends to add to your social circle. The awesome thing about being a taken man is that you can pre-emptively LJBF the hottest chicks, building a platonic stable which will have great potential if you ever become a free agent again. This subconscious knowledge alone will greatly affect your game, putting you in the necessary mindset to keep the attraction level high with your current lady.
I know you want to be faithful and that's commendable, but I feel compelled to add that you are 20 years old, hardly an age to get really serious with someone. I'd keep an open mind to meeting other females for the simple reason that you haven't truly lived yet, and this is the age where your drive is at its peak. Every guy needs a manwh*re phase, no better time than when you are in the same age bracket as hot, barely legal females.
Something to think about...
As for social settings sans the pickup, you will ease into that over time when your hormones calm down and sex isn't on the brain every 2 minutes. (I can go a whopping
6 minutes without thinking about it, lol)