When Dean left Stulls Cemetery, he didn't go straight to Lisa's.
He drove to Louisiana to kill a child-munching ghoul in Metairie, then drove a thousand miles to Gainesville, where he killed two vamps bent on turning a local football team.
After that, he swooped back to Reno, where a shifter was rumored to be working a local casino. Turned out to be just that, rumor, so he left the lady and drove on towards San Diego and a murderous witch.
He kept away from Bobby, and from Lisa.
Anything to stave off the reality that Sam wasn't coming back.