Did John LOVE Bob?
Okay, there are the couple obvious inferences of homo or bi-sexuality in regards to John Carpenter. But if John did kill Bob, could it have been a crime of passion? The crime of a jilted & unrequited lover perhaps?
We see John's reaction in the break-up scene, but did anyone catch that when John calls Bob later on the phone, just the sound of Bob's voice on the line causes John to reach for his crotch - and it's pretty obvious in the film that he's semi-pleasuring himself during this last phone conversation with Bob.
Did John love Bob? Was he supposed to be physically attracted to him? Or did all the years of sexual experimentation together just cause John to automatically associate Bob with sexual feelings?