I think that's definitely the way it's gonna play out. Of course Sonny will feel "betrayed" and leave poor Brenda yet again.
Wouldn't it be nice if for once Brenda had a brain in that pretty little head of hers, and told Sonny the truth? I would like to see the characters of Brenda and Sonny actually mature. They talk so much about how they aren't the same people, and how Sonny in particular has grown. Okay..I'd like to see that. It would be nice when Carly spills the beans, if Sonny can go and tell her to mind her own business. Imagine the look on her face if she thinks Sonny is "okay" with Dante and Brenda having been a couple.

Not that I think it will ever happen. The GH writers are known for beating a dead horse.

No doubt poor, missunderstood Sonny will make it all about him, and Carly will have the pleasure of saying "I told you so".