Well, he knows Zara's college aged, been looking around for a college, DeVere mentioned her, and Vassar, in the same conversation, CC lit up briefly, and DeVere is looking for digs near the college?
It's unlikely Zara's cheating on Earl with DeVere, she's strongly monogamous....
DeVere can't or won't swing digs on his own....
He either wants to get Zara a place to live near Vassar, or he wants to be near, himself, to keep an eye on her; kith-to-kith? A sluagh mentor?