Well then Calswimmer - we do seem to have a dilemma!
The witnesses to the marriage of John Perry and Charlotte Bohenna, in particular Eliza Penberthy, seem to confirm that she was indeed the daughter of Thomas and Catherine in which case she was baptised at St Ives 19th September 1802.
With her parents married in 1796 and three elder siblings it is probable that Charlotte was born within about 6 months or her baptism but certainly not before 1800 I should think.
And that makes the following from FamilySearch just a little awkward:-
Charlotte Perry buried 7th June 1837 St Paul, Bristol, Gloucestershire
Charlotte Perry buried 7th June 1837 Bristol, Gloucestershire
age 43There are actually three entries for this event in FamilySearch and each of them is different!
The first one is as above with the Parish names as St Paul and in this entry there is no mention of her age.
The other two entries are 'near identical' except that one has provision to say 'marital status unknown'. But both of these show her age as 43 which indicates she should have been born around 1794.
This is the only burial I can find in Cornwall or Gloucestershire for a Charlotte Perry so you might expect that it should be the wife of John. And it is just three months after the marriage.
The other point to consider is that it is also prior to the 1841 Census in which there appears to be no sign of Charlotte.
Leaving that dilemma just for a moment to display the other item I found which also helps narrow down when Charlotte may have died. This is again from FamilySearch:-
John PERRY, son of Francis Perry, married Mary GOODHIND, daughter of George Goodhind, 19th March 1842 at St Nicholas, Bristol, Gloucestershire
Niece Mary Webb therefore must be the daughter of a sibling of either John or Mary.
That record is reasonable evidence that it is indeed the same John Perry. After all, I don't think there were too many men around at that time with the name Francis Perry!, at least not in Cornwall where John was born.
So we know that Charlotte must have died sometime after her marriage in March 1837 and sometime before John's second marriage in March 1842. And given she cannot be found in 1841 then she must have died before June of that year.
The burial above is 'in the right place' but there is the problem of her age which suggests that it cannot be the right Charlotte Perry.
Of the other burials between 1837 and 1842 there are some in Staffordshire, Hertfordshire, Kent, Liverpool and Westminster in London which I think we can probably ignore quite safely.
And that leaves two:-
Charlotte Perry buried 23rd February 1840 Dowlish Lake, Somerset (no indication of her age)
Charlotte Perry age 37 buried 16th February 1838 St Giles, Reading, Berkshire
This last one I would think is just about right and of all that I have found is the most likely to be the one you want.
But I suggest you do not rely on FamilySearch or my word for it! Try to get a look at some originals of these if possible or at least some transcripts done by someone completely independent of the LDS people. By doing that you will at least know there are two separate sources you can quote.
BTW - Somerset and Berkshire both link geographically with Gloucestershire at some point.
CT