More than two-thirds of lawyers last year had at least one instance of a client using a private investigator to confirm or deny their suspicions that their spouse was cheating, according to new research by Grant Thornton's Forensic and Investigation Services practice.
Of those that used a private investigator, in 64 per cent of cases it was women checking up on their husbands.
Robert Kerr, forensic and investigation partner at Grant Thornton in Birmingham said: "Marriages are meant to be built on trust, yet this figure shows this is not always the case, as more than two-thirds of lawyers had clients who have used a private investigator to check if their spouse has been cheating on them.
"While it might seem like an extreme length to go to, people just want to know the truth - even if it hurts.
"Jimmy Choo founder, Tamara Mellon, was watched by private investigators hired by her husband Matthew Mellon during an acrimonious divorce in 2007.
"However, this is not just about the rich and famous - this is about everyday people using means to ensure they know if their spouse is being faithful."
For the fifth year in a row, extra-marital affairs was the main cited reason given by couples seeking a divorce.
During 2007, one third (29 per cent) of marriages broke down due to one partner being unfaithful, a reduction from 32 per cent in 2006.
Of those conducting extra-marital affairs, in more than two-thirds of cases (78 per cent) it was men who played away, a significant increase on 2006's figure of 69 per cent. In the remaining 22 per cent of cases it was women who cheated on their husbands - down from 31 per cent the previous year.
"Despite how affairs are viewed from a social perspective, they continue to be an ever present phenomenon, and have been the principal reason for the deterioration of marriages since our survey began five years ago," said Mr Kerr.
"As affairs continue to be the leading reason for divorces it is little wonder that the use of private investigators continues to grow."
However, for the first time since the survey began, the lawyers surveyed identified that mid-life crises were the second most cited reason for divorces, with 14 per cent attributing this as the cause of their clients' divorces, up from only two per cent last year.
In the majority of cases (93 per cent) it was men's mid-life crises that lead to the divorce, with the remaining seven per cent of cases attributed to women.
Family strains were the third most common reason behind divorce, with 11 per cent of lawyers outlining that this was the key cited reason for the marital break up of their clients.
Divorcing through the English or Welsh courts is still thought to be the most favourable place in the world for women, with an overwhelming 94 per cent of lawyers surveyed believing that women petitioning for divorce will receive the most favourable settlement there.
However, this is down from last year's result, where 98 per cent of lawyers thought women would receive the best settlement in England or Wales.
Of those remaining, five per cent of lawyers thought that women would stand the best chance in the US and one per cent reckoned the South African courts would be more favourable.
However, 28 per cent of lawyers suggest that men petitioning through the Scottish courts will receive the best overall settlement.
Mr Kerr said: "Given that pre-nuptial agreements are not legally binding in the UK, unlike in the US, it would be one of the prime motivators behind lawyers suggesting their clients petition through the US courts.
"However, if you're a man looking for the best settlement, then the results are somewhat more mixed, with Scotland remaining the clear favourite, but France, England/Wales and South Africa are bringing up the rear."
Nearly one third (31 per cent) of all divorces in England and Wales included the division of assets from outside the UK, up from 21 per cent the previous year.
"Given the ease with which people can buy assets abroad, set up offshore accounts or move between countries, it is not surprising that the number of divorces with international implications continues to grow," added Mr Kerr.