Complex sentence: In August 1827, he married Rosina Doyle Wheeler (1802--1882), a famous Irish beauty, but against his mother's wishes, who withdrew his allowance, so that he was forced to work for a living.
Split into simpler sentences: In August 1827, against his mother's wishes, he married Rosina Doyle Wheeler (1802--1882), a famous Irish beauty. When they married his mother withdrew his allowance and he was forced to work for a living.