Green’s Dictionary of Slang

1. (Aus.) to be having an affair.

1954

(con. 1940s) T.A.G. Hungerford Sowers of the Wind 150: She’s currently stabled with the bloke she’s dancing with, but as his wife’s coming up soon [...] I can’t see it lasting.

2. (US) for a pimp to enroll a prostitute in his ‘team’.

1969

‘Iceberg Slim’ Pimp 261: I never tried to stable her after that.