All of the couples I can think of:

Adventure Time with Finn and Jake
Finn and Princess Bubblegum
Lumpy Space Princess and Brad
Jake and Lady Rainicorn

Amazing Spiez
Lee and Braces girl (Don't know her real name)

Teen titans
Cyborg and Sarah
Starfire and Robin
Raven and BB or Terra and BB
Red X and Starfire

Sonic the hedgehog:
Sonic and Amy
Cream and Tails or Cosmo and Tails
Vector and Vanilla
Silver and Blaze
Knuckles and Rouge or Knuckles and Tikal
Shadow and Maria or Shadow and Rouge
Sally and Ken
Chris and Helen

Icarly
Carly and Freddy
Sam and Jonah
Spencer and Marrissa Bensin

Codename: Kids next door
Kuki and Wally
Hoagie and Abby
Nigel and Rachel
King Sandy and Mushi
Numbuh 90th century and Fanny
Chad and Cheer leader teen
Cree and Marice
4th Grade president Jimmy and Anna
Lizzie and Numbuh 65.3
Mega Mom and Distructo Dad (Chad's Parents)
Kuki and Ace the kid
Numbuh 10 and Numbuh 7
Mr. Fibb and Lasso Lass
Clip-Clop and Mr. Fibb

The marvelous Misadventures of Flapjack
Flapjack and Sally
K'nuckles and Bubby

6teen
Nikki and Jonesy
Jen and Jude
Caitlin and Wyatt
Reef and Fin
Emma and Johnny

Johnny Test:
Mary and Gil
Susan and BBB
Johnny and Sissy
Dukey and Missy

Spongebob Squarepants:
Sandy and Spongebob
Mr. Krabs and Mrs. Puff
Gary and Smellie

Phineas and Ferb:
Isabella and Phineas
Ferb and Gretchen
Candace and Jeremy
Stacey and Coltrane