Green’s Dictionary of Slang

(US) used as a euph. for fucking adj.

1962		(con. WWII) J.O. Killens And Then We Heard The Thunder (1964) 13: I want you to have every loving brother’s sister’s cousin’s child downstairs and standing at attention at six o’clock.
1966		D. Halberstam One Very Hot Day 51: You think we’re going to see any lovin’ Viet Congs today?
1977		J. Langone Life at the Bottom 76: ‘Eat and drink like a loving pig,’ he says, patting the bulge under his parka.
1995		J. Sack Company C 150: At long lovin’ last!