From today, just 100 guests will be permitted to attend wedding receptions.
It is part of the new Covid-19 restrictions announced on Friday.
It has meant that couples getting married in the next six weeks who have invited over 100 guests have to make some difficult choices.
Gavin Callaghan and Emma Blint are one such couple.
They are due to get married at Adare Manor in Co Limerick on New Year's Eve.
They live in Basildon in Essex in England, but both have family in Ireland.
"On my dad's side [I have family] from Sligo, and from my mum's side they're from Mullingar, and Emma's side are from Foxford, so when we thought about where to get married it just made sense to go to Ireland," Mr Callaghan said.
From today, just 100 guests will be permitted to attend wedding receptions. It means some couples due to get married in the coming weeks will have to make some difficult choices | Read more: https://t.co/SjiemV9WBR pic.twitter.com/WOQvW4MPYM— RTÉ News (@rtenews) December 20, 2021
They have invited 125 guests to their wedding, many of whom are travelling from England, and they were taken aback at Friday's announcement.
"People have booked their flights, booked their PCR tests, their accommodation, everyone is playing by the rules and having a quiet Christmas, looking forward to the wedding," Ms Blint said.
As they look at cutting around 20% of their invitees, the couple is concerned that those who have already paid for flights and accommodation will lose out financially.
"Because travel is not going to be restricted, they will get no money back from the insurance companies so they will lose that money," Mr Callaghan said.
They are also frustrated at the lack of detail available on the new rules.
"We were trying to clarify yesterday whether children are counted as part of that number and no one seemed to really know, because it [the announcement] is made at six o'clock on a Friday night and then everyone goes home until Monday, and you're just left in this purgatory," Mr Callaghan said.
The couple have been planning their wedding for three years and they have already postponed it once before.
They say they always knew that "Covid was going to be a part of the story of our wedding", and that they understand and share concerns about an upsurge in cases and the Omicron variant.
"We can understand logical policy making and we can fully understand PCR testing, and wanting our guests to take daily antigen tests, all of that makes sense," Mr Callaghan said, adding that all their adult guests are "triple jabbed".
However, the couple described it as "illogical" that a limit is applied to the numbers that can attend a wedding reception and not a wedding service for example.
"You can have, we think, as many people as you like, pack into a small church for the ceremony, but 20 minutes later you can't have that same number of people enter a huge ballroom with better ventilation and more social distancing," Mr Callaghan said.
Editor of wedding website 'One Fab Day' Celina Murphy spent the weekend fielding calls from many couples with similar complaints and queries.
"Couples at the minute seem to be pretty desperate to hold onto their current number of guests," Ms Murphy said.
"We've had lots of questions about when the reception technically begins ... we've also been repeatedly asked if children are exempt from the 100 cap, which unfortunately they're not," she added.
"Cutting 50 or 150 guests from your wedding with a few days' notice is so tricky ... some couples had literally 42 hours in which to do it," Ms Murphy said.
"Many guests will have booked annual leave, accommodation and babysitters for the wedding well in advance, so it's not the minor inconvenience it might seem to be."
Gavin and Emma are still hoping the Government will "scrap the cap".
So far, the couple have not been able to bring themselves to cull their guest list.
"At some point either today or tomorrow, we're going to have to start making some very difficult phone calls and text messages and hope to God for some understanding from our friends and family," Mr Callaghan said.