It's not too difficult to picture - and believe me, we have pictured it - that two of the sexiest actors in Hollywood, after spending day-after-day on set, finally get jiggy with it.
And sneaky off-screen canoodles are basically inevitable. What's harder to picture however, is when those off-screen saucy antics are occurring between on-screen relatives.
Sadly, their relationship has now ended, but they were very much in love when shooting this movie!
Dated: 2004 - 2006The pair got together while playing brother and sister in Everwood and dated for some time.
Did you remember the one-time rom-com queen and Grey's Anatomy star was in Roswell?
She went on to conquer Hollywood in films Knocked Up and 27 Dresses.
Amazingly, it takes a year of dating for them to realize they've already met.
(Ah, doesn't it feel like it was just yesterday Max saved Liz's life in the Crashdown diner?! " Appleby captioned an adorable photo of the duo on Instagram.
"And that's not to blame anyone or whatever else, I'm just saying everyone gets their time and then you're gone, but it was one where I felt there was so much more potential for that show to go on longer.
"I was at the Science Center with my kids in Vancouver, and he just tapped me on the shoulder, and it took me a minute to realize it was him! "But would she want to take on the character of Liz again? "I think we all feel in some small way that we were cut short," he said.
He's since been 'that guy' you know in the background of Guardians of The Galaxy and X-Men First Class, and enjoyed more screen time on CSI: Miami back in the day.
Another TV couple that played brother and sister — Katherine Heigl and Jason Behr portrayed siblings on Roswell and began dating in 1999.