To be honest, I'm not all that for abortion for stupid people. However, I am against pressuring a girl who wants to have an abortion into not having one. This isn't a parent's decision, a boyfriend's decision, its the pregnant girl's decision. I'm not gonna get into ethics. Its the law.
Personally, if he's telling the truth, then its his own damn fault for drinking and not using a condom. And its her damn fault for drinking, letting him have sex with her without a condom, and not having enough sense to take a morning after pill.
And I still don't believe him if its only been 4 days.