Could it be possible that between 1825 and 1829 she did indeed marry,
became a widow and re married shortly after.?
Second marriages were almost necessary for widows with children,life was hard and women paid lower than men.
I know you have searched extensively but my paternal G. Grandmother appears in the 1891 census as a widow,but she was not, her second marriage must have broken down as she had moved from Nottingham to M/c
with her son who had his real name but hers is totally different,not her maiden name ,not her married name nor her second married name described as a widow ,whilst her second husband is on a boat off Hull saying he is unmarried!!!
But It would be strange for the priest not to know and parishioners not to comment as banns would surely have been read.
Perhaps she went into service out of her area so those years between would not be known to all and sundry .
What a mystery,that will keep you out of mischief for a year or two!
Do let us know how you go on.
Viktoria.