The couple that sprang immediately to mind is Wrath and Beth from JR Ward's Dark Lover. (Yes, I am a dude, and I have read paranormal romance. Molon Labe.) The attraction between the Blind King and his shellan is at once tender and terrifying, and is so well-written by Ms Ward that her subsequent stories suffer from comparison.
For absolute devotion, Popeye the Sailor Man is one in a million. He doesn't care that Olive Oyl is sort of plain and constantly in danger of losing her virtue to men with smooth ways and glib lines - Popeye loves her without reservation. And once her Sailor Man has rescued her from the disaster of the day, she invariably covers him with kisses and forgives him for his fighting and muttering. It's a good relationship.
But then, the books that I read do not focus on relationships. If any sort of romance exists at all, it is secondary to the tale. Wilbur Smith's novels often have a strong romantic subplot, but those typically end in disaster. W.E.B. Griffin introduces great female characters, but they are unrealistically subservient when they are not unrealistically strong.
But a good balance is struck by Rissa Kerguelen and Bran Tregare in F.M. Busby's YA books. Tregare starts out as a complete ass and rapist, but eventually mellows to make a real partnership with Rissa. And after all, partnership is what it's all about!
Note from Gypsi: He's ratted us out! Our guilty pleasure is J.R. Ward's Black Dagger Brotherhood series. Shh! Don't tell anybody!
Second note from Gypsi: This was in response to my challenge for him to do a Top Ten Tuesday favorite couples, too.