Now into speculative territory, a Robert Whitten given as born on 14 December 1832 was baptised in Clare Presbyterian Church on 16 January 1833, the parents were Robert Whitten and May Ann McMaghin of Marlacoo.
Edited to add:
Also, a Robert Whitten of Marlacoo, the son of Robert Whitten a stonemason, married a Susan Willis of Marlacoo (father William a farmer) in Ahorey Presbyterian Church on 27 December 1855, maybe a brother of John.
There was also a marriage on 22 December 1853 in Mullabrack Church of Ireland of an Isabella Whitten of Marlacoo to a Charles Houston, her father was given as Robert Whitten, a mason.
And a marriage on 8 December 1862 in Mullabrack Church of Ireland of an Alice Whitten of Marlacoo to a Joseph McClean, her father was given as Robert Whitten, a mason.
And a marriage on 6 April 1863 in Ahorey Presbyterian Church of a William Whitten of Marlacoo to a Caroline Walker, his father was given as Robert Whitten, a stone mason.
And a marriage on 6 April 1864 in Ahorey Presbyterian Church of a James Whitten of Marlacoo to a Sarah Jane Wylie, his father was given as Robert Whitten, a stone mason.
There's clearly a cluster of Whittens (and Wolseys/Woolseys) in the more general area (eg. go look at the 1901 and 1911 censuses and PRONI Will Calendars), however two indicators for your Whitten line so far are the location Marlacoo and the occupation stonemason.