Spoiler well, it's not JUST 'they're not used to being apart', it's also that they're onboard an enemy ship and worried sick about the other's safety.
Spoiler true but they also have Steven right there who's a child and knows nothing of Homeworld gems but their priority is still reuniting with each other.
Spoiler: more specifically We know for a fact, from Three Gems And A Baby, that they briefly unfused as recently (for given values of "recently") as Steven's infancy--it's implied that the reason she wanted to wait so long to tell him she was a fusion was that Babby Steven got confused and scared when she unfused. I'm positive that they'd unfused at some point before then--like you said, Greg's met them--but yeah, it's worth noting that they did unfuse in canon before the events of Jailbreak (chronologically, that is).
Peridot this episode- Spoiler I’ll kick anyone’s ass. I’ll kick your ass. I’ll kick your Diamond’s ass. I’ll kick my own ass.
Spoiler oh hey, that's why The Andy Episode was a thing. An estranged relative with questionable beliefs? It was setting up the diamonds!
FUCK FUCK FUUUUCK I just realised the deal with the shooting stars!! Spoiler: Recent events + hindsight It's the nursery rhyme! Everyone knows it, but we didn't think - Twinkle twinkle little star How I wonder what you are Up above the world so high Like a Diamond in the sky
Spoiler Posting the lyrics of a song isn't necessarily a spoiler, but posting lyrics that match up with a particular plot twist is a spoiler, especially if you bold the most relevant parts of them.
Spoiler ...the crystal gem logo is a star and that was always a bit odd because even though they’re aliens they’re really Earth-focused and this pulls it together and I hate it
Spoiler Whenever there was a shot up at the night sky, particularly from season 3 onwards, there would be a shooting star. There was some speculation that this was some kind of foreshadowing, particularly that it heralded the arrival of some big important Homeworld invasion, but nobody could figure it out for sure. And I mean, the nursery rhyme is still just a theory, so I could be wrong. *le shrug*
Early Peridot characterization (ala back to the barn - message received) is obviously based loosely off Karkat, right? I just noticed another connection - Peridot is lime green. Karkat's a mutated limeblood. We're all homestuck trash, yo XDD
Spoiler: reunited (and a homestuck joke) i found this on tumblr and it's killing me so i felt the thread needed to see it
She's also based on Rebecca's Invader Zim fanfiction. That's not a joke, that's an actual thing. (I do think Karkat influenced her too, though--the bit in Log Date 7-15-2 where she makes the shipping chart and tears it up has like, an actual Karkat expression. Also note that Lauren Zuke was a boarder on that one and is known to be a filthy Homestuck, so...)
I made it a tumblr post! Spoiler http://tickingnectarine.tumblr.com/post/175816955979/ill-kick-anyones-ass-ill-kick-your-ass-ill