on with, phr. — Green’s Dictionary of Slang

on with phr.

also on together

having a relationship with.

1849		Thackeray Pendennis I 111: ‘I wonder whether she is on with Sir Derby Oaks,’ thought Bows.
1898		Truth (Sydney) 5 June 2/4: Some fifteen months ago he mashed a young, plump, and pleasing person [...] She was ‘on with him’, as girls of her class call it, for twelve months.
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 107: On with: in push circles, keeping company on [sic] courting is spoken of as ‘I am on with her’, ‘She is on with me.’.
1905		Sun. Times (Perth) 17 Dec. 1/1: The Highgate Hill Venus is on again with the old love.
1910		L. Esson Woman Tamer in Ballades of Old Bohemia (1980) 67: Wasn’t he on with Katie before?
1938		N. Lindsay Age of Consent (1973) 100: ‘No doubt she was on with Dinny Ryan the time she got put up the flue’ .
1945		N. Lindsay Cousin from Fiji 215: ‘Didn’t you know your cousin was on with Darky Tyrell?’ [Simes:DLSS].
1959		G. Hamilton Summer Glare 68: All the boys in town are on with her.
1961		J. Rose At the Cross 17: [A] pretty girl called Milly, who it appeared was ‘on’ with another girl [Simes:DLSS].
1969		A. Buzo Rooted I iii: I’m on with Simmo now. We’re going to make it together.
1977		B. Davidson Collura (1978) 103: Collura was on dead center with Dante Diamonds.
1978		P. Kenna Furtive Love (1980) 8: George: Everybody knows we’ve been on together since Brisbane [Simes:DLSS].
1981		P. Corris White Meat 177: ‘Did you know he was on with the Baker woman’ [Simes:DLSS].
1987		Eble Campus Sl. Oct. 5: on – continuing a relationship: Are you still on with her?
1987		K. Lette Girls Night Out 87: ‘Hey, aren’t you one of the Sushi sisters? Are youse chicks on together?’.
1997		T. Ayres (ed.) Hard 97: Rumours spread about Jo and me being on together. It worked perfectly [Simes:DLSS].
1999		N. Drinnan Pussy’s Bow 69: ‘[H]e was sort of on with Doc but it seems to have petered out’ [Simes:DLSS].
2003		McGill Reed Dict. of N.Z. Sl.
2007		L. Redhead Cherry Pie [ebook] ‘t looks like your husband was on with her’.