If you publicly kill her off, you get years of breathing space while you "grieve."
Still seems like attention-whoring to me. Too media-driven.
Maybe he did it for both reasons:
1. Started it to hide his sexuality
2. Heisman campaign started (early season)
3. Media started flocking to him due to his own and team's year.
4. Heisman campaign in full force, strongly competing with Johnny Football.
5. Campaign could use a spark, some extra publicity.
6. Media/Family start asking more and more about the girl.
7. Starts to panic. Claims she's gotten sick
8. Grandmother dies
9. Already grieving, sees way out and "kills off" his "gf".
10. Double the tragedy, double the media attention
11. Also stopped questions. Two birds, one stone.
:dunno: It's possible, I suppose. I do think it's quite obvious he was in on it, if nothing else.