One in three wedding guests are declining invitations due to rising costs, with nearly half of Generation Z and 43 percent of millennials reporting financial reasons for their refusals. August is currently the most popular month for weddings.

The average cost for a single wedding guest is approximately £316, and more than 12 percent of guests spend upwards of £500 at the last wedding they attended. For individuals attending multiple weddings, such as 15 percent of Gen Z who expect to attend three ceremonies, the financial burden can exceed £1,000.

To manage these expenses, 16 percent of guests have reduced spending on luxuries, 14 percent have cut back on everyday purchases, and 11 percent have stopped buying new clothing altogether. While 14 percent of the 2,000 surveyed guests felt relieved after declining an invitation, 8 percent experienced guilt and 5 percent reported fear of missing out.

Another 15 percent of guests indicated they were tempted to decline but attended anyway, absorbing the costs. The trend of destination weddings, popularized by celebrities, also contributes to the financial pressure on attendees.

"Weddings remain joyous and memorable occasions, but they can leave a dent in your wallet," said Duncan Fortune, head of commercial at Tesco Bank, which conducted the research.