The pure panic in Matthew's expression because Taylor cannot lie to save his life or stop yapping

Dream : "Excuse me ?"

Y/N : "Why not The Sleeping ? Or The Nightmaring ?"

Dream : "You can sleep without dreaming, and dream is the common name."

Y/N : "You could find a name for 'good' dreams, since nightmares are 'bad' dreams."

Dream : "The Reverie."

Y/N : "So The Revering."

Dream : "No."

Y/N : "But why not Nightmaring ? Cori would love it."

Dream : "No."

Y/N : "That's nightmarist."

Dream : "Go to sleep."

Y/N : "With or without you ?"

He doesn’t get there on his own, Matthew helps. Unwittingly. A little bit wittingly. Look, he just needs these two idiots to get their shit together sometime this century, okay? So Dream asks Matthew how humans in the waking ward off the unwanted advances of others. For Hob, because Hob always turns down these hopeful humans with their lurid daydreams, so wouldn’t it be easier if he had some sort of way to make sure everyone knew that he wasn’t interested? It’s for Hob’s convenience only, and in no way about his own inappropriate possessiveness. Hob was HIS, and everyone needed to know that. 

So Matthew is like... uh, I guess a ring on his left hand fourth finger would do that? But that has a really specific meaning that you might ant to talk over with Hob first, boss, okay? 

Dream obviously does NOT talk it over with Hob first, just sweeps in and slips the (beautifully crafted) ring on his finger and says it’s to protect him from unwanted attention.

So Hob thinks it’s some kind of supernatural protection thing and that Dream doesn’t know what it means to humans. After all, the idea of wedding rings is relatively new, right, to a being as old as Dream? So he wears it, wanting it to mean something it doesn’t and knowing it will make it impossible to move on for as long as he does, because everyone thinks he suddenly got married and is off the market.