Sometimes Sam wonders if he isn't still trapped in one of Gabe's little dreamworlds. Everything is so impossibly perfect. Waking up every morning next to the diminutive Archangel is like waking up with the sun in your bed- warm and bright and just good. And one of the many pluses to Gabe's powers is that they both wake up without morning breath, so their "good morning" kisses taste like cotton candy or strawberry jam instead of spoiled eggs. Then of course there's the wake-up sex (which is mind-blowing), followed by a quick shower that usually turns into a long bout of shower sex.
It's a great way to start the day, despite the reproachful glances they both catch from Bobby for using all the hot water, and from Dean for scarring him with their noises. ("Worth it," Sam whispers in Gabe's ear as the Archangel pours himself some Coco Puffs.)
They still hunt, of course- there are still monsters, but nothing's threatening to rip the world apart or possess the Winchesters or eat all the souls in Purgatory. Even Dean is actually very nearly happy- and that confused Sam until he caught his brother necking with Cas in the Impala.
All in all, things could be called peaceful. Pleasant. Idyllic.
And that scares the crap out of Sam.
He starts wondering if maybe this isn't real. If he's caught in some Inception situation or really lengthy hallucination or if he's in a coma or if he's dead and this is Heaven. It worries him.
Then Gabriel goes and does some stupid thing- it doesn't matter what; he might've turned Bobby into a kitten or wiped out a biker gang for making eyes at Sam or turned Sam's salad into a chocolaty mess. Whatever it is, it's enough to make the tall human snap and pitch a bitchfest at his boyfriend, who just stands there looking suitably chagrined (and then grinning deviously when Sam turns away).
It takes Sam a few times to realize that he actually loves it when Gabe does this. It lets him know that he can still get royally pissed at his lover. Lets him know that Gabriel isn't perfect. That this is all real.
("Hmm, well, I must be forgiven. You're grinning so hard your head's about to fall off, kiddo." "Shut up, I'm still mad at you." "Sure you are, sugar. Does that mean we can get to the angry sex?" "...Yeah.")