Superhero couples

Green Arrow and Black Canary (JLA and solo titles)
Hawkeye and Mockingbird  (west coast Avengers soon in title 2gether)
Fly and Flygirl (Red Circle) (Mighty Crusaders and solos's)
Liberty Belle (Original) and Johnny Quick (ASS)
Arn Munro and Phantom Lady (Sandra Knight) (Freedom Fighters Mini)
Yellow Jacket and Wasp   (Avengers)
Dick Grayson and Korianda (Starfire) (Teen Titans and Titans)
Firestorm (Ronnie) and Firehawk (solo title intoed to JLA)
Black Adam and Isis (POS JSA)
Jean Grey and Scot Summers  (Xmen titles)
Banshee and Moira Taggart  (Xmen Titles)
Ultra Boy and Phantom Girl  (LOSH)
Lightning Lad and Saturn Girl  (LOSH)
Amazingman II and Maxima  (Extreme Justice)
Captain Atom and Plastiquie  (Extreme Justice)
Guy Gardner and Tora oslander (ice) (JLI )
 
Just off the top of my head. Not all are still current. I'm pretty sure there are a few more in Legion of Superheores.

Reed and Sue Richards, Hulk and Betty, Thor and Sif, Hellstorm and Hellcat, Silver Surfer and Shalla-bal, Black Colt and Medusa Hal Jordan and Carol Ferris, Barry Allen and Iris, Thanos and Death, Superman and Lois, Batman and Catwoman, Joker and Harley Quinn, Frankie Ray and Galactus, Aquaman and Mera, Alan Scott and Rose Thorn, E-man and Nova Kane, Nova and Namorita, Wonder Woman and Steve Trevor, Quicksilver and Crystal, Havok and Polaris, Rogue and Gambit

I forgot 
Vision and Wanda

Atom Eve and Invincible.
Superman and Wonder Woman.

luke cage & jessica jones cage 
misty & iron fist  
blade & spitfire  
does cloak & dagger count? aren't they a couple ? 
colossus & shadowkat 
cyclops & emma  
bucky & black widow  
tony stark & any woman 

Haha, Tony Stark & any woman. :-D

Vision 2.0 and Stature.