here's what I think happened: Boyfriend's away on Active duty, she cheats on him bangs another dood, hell maybe she was even leading this guy on in an affair because she was lonely but she gets pregnant. Boyfriend who is away either doesn't know it's not his, or doesn't care that it's not. Either way father of child is outraged when she tells him she's keeping the kid and not choosing him over her BF who is away, and dood decides to get revenge.
Here's what makes this theory plausible for me:
1. they do not reveal who the father is in the article
2. stabbing someone is a very personal emotional act, would this guy be *this* outraged because she didn't pay him some money?
This doesn't make any sense, though I am not excusing what this guy did.