If your girlfriend is pregnant and you decide you don't want to be a part of the child's life, just imagine what being that child would be like. That child will be an adult one day. They'll have to explain to everyone that they don't know you. When they're little, they'll wonder where you are. As they grow, they'll convince themselves that it's okay. They'll see you marry some other woman some day. They'll see you have other children. They'll watch as you raise those other children. They'll feel so confused, trying to sort out their feelings. Feelings about their half siblings that they'll never know. Resentful feelings about the fact that you chose to raise their new kids. Confusion on why you did it for the new kids, but not for them. They will cry the night they realize that they don't know what your favorite color is. Keep all of this in mind when you decide not to stay in a child's life.