Hi ms8008y,
When Ruth Sweet married Walter Wheller on 26 December 1822 she was under-aged and needed her parent's consent to marry. She was therefore born between 1801 and 1804. Charlotte Vigar died in childbirth in 1796 and so cannot possibly be the mother of Ruth.
John Sweet remarried in 1800 to Ruth Chard (the widow of Anthony Chard and Charlotte Vigar's sister). BTW John's first wife Elizabeth Vigar was Charlotte and Ruth's first cousin. Under the law at the time such a marriage (to a dead wife's sister) was voidable under ecclesiatical law. I believe that this is why the marriage took place in Bristol - being the nearest place to Pitney that was not in the same diocese, thereby making a challenge difficult. The evidence that this marriage is of John Sweet and Ruth Chard of Pitney, and not just a coincidence of names, is in the Pitney manorial rent records of 1801 where Ruth's holding (inherited from Anthony Chard) is transferred into the name of John Sweet.
John Sweet died in 1830 and was survived by Ruth. In the 1841 census she can be found living with her son George Chard. She died in 1841.
I hope this is helpful.
Regards,
Grahame.