Kate Duff, wedding and event planner and founder of Hitch Perfect, tells us that the most common faux pas of wedding guests is RSVPing late.

"This is a big source of stress for couples, as it makes final preparations difficult—not to mention costly when you think about the fact that most couples pay per head!" she said.

"Bringing along uninvited kids is another major faux pas," Kate adds. "Most couples these days specify on their invitations whether children are welcome or if it’s an adult-only affair. Many prefer the latter due to the interruptions that can occur during the ceremony!"

One more serious mistake that wedding guests are guilty of committing is arriving late. "Wedding day timelines are very carefully created to ensure the ceremony happens seamlessly—there are many events that need to happen to make up a wedding day so late guests can cause unwanted delays. It’s for this reason that timelines often include buffers for tardy guests," Kate explained.

Fortunately, the bride and groom can avoid poorly behaving guests on their special day by managing expectations early, said Kate.

"On your invites or wedding website, include clear directions on dress code, plus-ones, ceremony start time, and any other key details. Appoint a key contact for the day of the wedding to handle any guest-related issues. This is usually your wedding planner. However, if you’re planning the wedding yourself, identify a trusted family member or close friend to keep an eye on things," she suggested.

Kate also strongly recommends couples utilize a master of ceremonies (MC) to prevent guests from ruining their event. "Many MCs will ask the couple ahead of time whether there are any guests to ‘watch out for.’ If you have an attendee that you know can be trouble, have a word with your MC to make sure no impromptu speeches or unsavory song choices make the cut."

Even with all these precautions in place, there's still a chance that there will be guests that the couple will regret inviting. They can avoid this by setting priorities while planning the wedding. "This is particularly important for the guest list. If you value a more intimate, close-knit celebration, use this to guide your decisions on invitees," Kate said.

"Consider whether you can realistically see them in your life in 10 years," she further advises. "Your wedding day is a once-in-a-lifetime—make sure your guests are reflective of the importance of the occasion. This is particularly useful when considering whether to invite work colleagues."

Lastly, Kate encourages couples to stand firm on obligation invitations. "You don’t need to invite someone because you went to their wedding. You don’t need to offer a plus one or allow children to attend. Keep in mind that this day is about you!"