• Boomer and The Chief (BSG)
• Apollo and Starbuck (BSG)
• Rachel and Ross (Friends)
• Veronica and Logan (Veronica Mars)
• Rory and Jessie (Gilmore Girls)
• Sid and Cassie (Skins)
• Seth and Summer (The OC)
• Chuck and Blair (Gossip Girl)

I'm sure there are more but I can't think of any at the moment (probably because i don't watch that much tv, should've done a movie list actually...) so I'll add to this later.