Romantic relationships, reciprocated or not.

Superman

• Lois Lane, Superman's wife
• Lana Lang, Clark Kent's childhood romance
• Wonder Woman, often paired with Superman romantically
• Lori Lemaris, Clark Kent's college sweetheart
• La Encantadora
• Big Barda, forced into making an adult film
• Dana Dearden
• Maxima, finds Superman worthy of fathering a child
• Luma Lynai
• Chloe Sullivan
• Lyla Lerrol
• Lyra 3619
• Zara
• Lola-La
• Loana, mother to Van-El in the Superman: The Animated Series version of "For the Man Who Has Everything."
• Cat Grant, dated Clark Kent
• Orella, almost married in Superman #180 (October 1965)

Supergirl

• Ethan
• Ago
• Jimmy Olsen
• Brainiac 5
• Captain Marvel (Freddy Freeman)

Jimmy Olsen

• Chloe Sullivan
• Lucy Lane
• Supergirl

Lana Lang

• Clark Kent
• Whitney Fordman
• Pete Ross

Superboy

• Tana Moon
• Roxy Leech
• Wonder Girl

Lex Luthor

• Matrix
• Lana Lang (in Smallville)
• Contessa Erica Del Portenza