I have often looked for a definitive answer to your question.
I found this information as a source in a bibliography at this link
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https://dalspace.library.dal.ca/bitstream/handle/10222/10256/Arnup%20Research%20100%20Years%20of%20Marriage%20EN.pdf?sequence=1&isAllowed=y
See Snell and Abeele, "Regulating Nuptiality," for details of this legislation. Under common law, the minimum age for marriage was twelve for females and fourteen for males. That age was raised to fourteen for both sexes under the 1896 Marriage Act. (1896) 59 Vict., c. 39, s. 16.
also on Wikipedia
https://en.wikipedia.org/wiki/Marriageable_age
In the 12th century, Canon law jurist Gratian, stated that consent for marriage could not take place before the age of 12 years old for females and 14 years old for males; also, consent for betrothal could not take place before the age of 7 years old for females and males, as that is the age of reason. The Church of England, after breaking away from the Roman Catholic Church, carried with it the same minimum age requirements. Age of consent for marriage of 12 years old for girls and of 14 years old for boys were written into English civil law.
After the 1759 Battle of the Plains of Abraham the British were in charge and I believe that what was in English civil law would have been the rule in New Brunswick.
My husband's several times GGM, married at the age of 14 or perhaps 15 on 18 Oct 1844 in Upper Canada.