The world of Videogames

There are so many iconic videogame couples and therefore so many opportunities for Cuckqueanary

Mario and Peach, Luigi and Daisy, Zelda and Link (that one covers multiple couples), Cloud and Aerith from Final Fantasy 7, Chloe and Max from Life is Strange (we could have a lesbian cuckquean), Geralt and Yennefer. There's so many Choices when it comes to Commander Shepherd, or the Fallout franchise

And so many more (my mind's gone completely blank right now)

With time travel shenanigans you could have Link Cucking Zelda with other incarnations of Zelda! (Just an idea) and there's so many possibilities with crossover franchises like Smash Bros. The possibilities are nearly endless