Hi Lisa,
in case you havent seen them here's some prior threads that may be relevant to you.
http://www.forum.forest-of-dean.net/index.php?id=4065
http://www.forum.forest-of-dean.net/index.php?id=3123

From LDS I find:

groom's name: George Gettim
groom's birth date:
groom's birthplace:
groom's age:
bride's name: Hester Osman
bride's birth date:
bride's birthplace:
bride's age:
marriage date: 06 Sep 1764
marriage place: Chapel Hill,Monmouth,England
groom's father's name:
groom's mother's name:
bride's father's name:
bride's mother's name:
groom's race:
groom's marital status:
groom's previous wife's name:
bride's race:
bride's marital status:
bride's previous husband's name:
indexing project (batch) number: M03337-2
system origin: England-ODM
source film number: 104863
reference number:

NB different date ?

And from searching Gethins of Monmouthshire, their family ?

https://www.familysearch.org/search/record/results#count=20&query=%2Bsurname%3Ageth...

name: Sarah Gethin
gender: Female
baptism/christening date: 19 Nov 1772
baptism/christening place: CHAPEL HILL,MONMOUTH,ENGLAND
birth date:
birthplace:
death date:
name note:
race:
father's name: George Gethin
father's birthplace:
father's age:
mother's name: Hester
mother's birthplace:
mother's age:
indexing project (batch) number: C03337-1
system origin: England-ODM
source film number: 104863

name: Littleton Gethin
gender: Male
baptism/christening date: 19 Nov 1772
baptism/christening place: CHAPEL HILL,MONMOUTH,ENGLAND
birth date:
birthplace:
death date:
name note:
race:
father's name: George Gethin
father's birthplace:
father's age:
mother's name: Hester
mother's birthplace:
mother's age:
indexing project (batch) number: C03337-1
system origin: England-ODM
source film number: 104863

name: William Gethin
gender: Male
baptism/christening date: 19 Nov 1772
baptism/christening place: CHAPEL HILL,MONMOUTH,ENGLAND
birth date:
birthplace:
death date:
name note:
race:
father's name: George Gethin
father's birthplace:
father's age:
mother's name: Hester
mother's birthplace:
mother's age:
indexing project (batch) number: C03337-1
system origin: England-ODM
source film number: 104863

These records are also listed in this FoD site's PRs, the only Gethins listed for Chapel Hill I think. Other Chapels give:

Record_ID: 330482
Entry_Number:
Year: 1773
Month: Aug
Day: 29
Surname: GETHYN
Forenames: Sarah
Residence:
Age_at_death:
Officiating_Minister:
Event: Burial
Cause_of_death:
Memoranda: d/o Geo Gethyn
Notes:
Register_Reference:
Page_No:
Parish_Chapel: Tintern Monmouth
Soundex: G350

Record_ID: 330484
Entry_Number:
Year: 1773
Month: Sep
Day: 8
Surname: GETHYN
Forenames: William
Residence:
Age_at_death:
Officiating_Minister:
Event: Burial
Cause_of_death:
Memoranda: s/o Geo Gethyn
Notes:
Register_Reference:
Page_No:
Parish_Chapel: Tintern Monmouth
Soundex: G350

Record_ID: 330512
Entry_Number:
Year: 1783
Month: Oct
Day: 5
Surname: GETHYN
Forenames: Littleton
Residence:
Age_at_death:
Officiating_Minister:
Event: Burial
Cause_of_death:
Memoranda: s/o Geo Gethyn
Notes:
Register_Reference:
Page_No:
Parish_Chapel: Tintern Monmouth
Soundex: G350

Such a sad tale !.
Why isn't Hester mentioned in their Burial Records ?. Is this normal or had she died or left ?

Using the Advanced search for Baptisms for "Geo Gethin", also gives following Baptisms:

198198 1765 GETHIN Robert Geo Esther Tintern Tintern Monmouth
198209 1766 GETHIN Geo Geo Esther Tintern Tintern Monmouth
175782 1775 GETHING James George Hester Chapel Hill Monmouth
175799 1777 GETHING William George Hester Chapel Hill Monmouth

198373 1793 GETHIN Littleton Geo Mary Tintern Tintern Monmouth
198380 1794 GETHIN Amelia Geo Mary Tintern Tintern Monmouth

I suspect the latter two are to George "Junior" from 1766 birth above.

Back to LDS, could this be George, Esther's husband, father of George b1766 ??
A common name maybe but not too far away..

name: George Gethyn
gender: Male
baptism/christening date: 08 Apr 1736
baptism/christening place: CAERWENT,MONMOUTH,ENGLAND
birth date:
birthplace:
death date:
name note:
race:
father's name: George Gethyn
father's birthplace:
father's age:
mother's name:
mother's birthplace:
mother's age:
indexing project (batch) number: P01049-1
system origin: England-ODM
source film number: 104853

Could this be his subsequent marriage ?.
Given the date and locality near Monmouth I can't help think it's linked ??

groom's name: George Gethin
groom's birth date:
groom's birthplace:
groom's age:
bride's name: Mary Simmons
bride's birth date:
bride's birthplace:
bride's age:
marriage date: 1761
marriage place: Itton, Monmouth, England
groom's father's name:
groom's mother's name:
bride's father's name:
bride's mother's name:
groom's race:
groom's marital status:
groom's previous wife's name:
bride's race:
bride's marital status:
bride's previous husband's name:
indexing project (batch) number: M03351-2
system origin: England-VR
source film number: 104873
reference number: 2:V7BV15

Itton is in the right area, very near Chepstow just down the Wye from Monmouth etc.
http://www.genuki.org.uk/big/wal/MON/Itton/index.html

Hope this helps a little, altho' perhaps not as George is clearly a popular (family?) name !
as shown by this Baptism from LDS !

name: George Gethyn
event type: Baptism
event date: 14 Aug 1692
event place: Mathern, Monmouthshire, Wales
age:
birth year (estimated):
spouse's name:
gs film number: 2419401
digital folder number: 004393256

Again, Mathern is the right area, very near Chepstow.
http://www.genuki.org.uk/big/wal/MON/Matherne/index.html

Thank you so very much Jeff it put all my research in to place, I do believe George snr was married before he married Ester, from the dates given I think I have made progress and believe George Snr was the son of George and Joyce.

I become's a nighmare when there are so many George's

Thank you so very much