Sorry, but I can't agree with some of these opinions. The best advice you can give him is to just say "fyck it" and give up his life to raise some kid? Fyck that man. Do you best to convince her to get an abortion. At 3 weeks, whatever is inside her is nothing close to resembling a human. Hmmmmm, ruin your entire life, or get rid of an embryo? Hard choice....Next thing you now, these guys are going to tell you not to jerk off because of the millions of sperm that die every time you ***. Give me a break.
If you can't convince her to get the abortion, don't leave her, stay with her. Try to stress the hell out of her to force a miscarriage. Try to slip something in her drink to fyck up the kid, something man.
Besides, if she's young, chances are she isn't really thinking straight and will probably thank you later for convincing her not to have the kid.
I know I'm gonna get flamed to shyt for this, but all these guys saying "just raise it, be a man" Yeah whatever, lets see what YOU guys say when YOU get a chick pregnant.