Green’s Dictionary of Slang

(W.I.) a faithful lover.

1932		C. McKay Gingertown 228: ‘Why no get you one stucky?’ he was asked.
1933		(con. 1900s) C. McKay Banana Bottom 317: Stucky: sweetheart.
1983		T. White Catch a Fire 123: Young bloods [...] their ‘stuckies’ (girlfriends) joined to them just below the waist.