4 years thrown away just like that. Kiss the guy in front of his friends somemore. Your gf must be very easily influenced. I know 4 years is a very long time. I admit that and it's very hard to let go but in our mind, we should because someday if she becomes your way, same scenario may repeat - especially she is easily influence.

But because of love, we do stupid things and it end up hurting ourselves. Maybe today, maybe tomorrow, maybe years down the road.

The fact that they celebrated both their birthday together, kissed and then, tell you she wants freedom and yet come back to TRY to use you to support the guy who already has a gf - obviously your gf is stupid, one-sided and being played.

Let her save herself. Meanwhile, you save your's. Dont limit your life to just one girl man. If she is not good enough for you, move on!