And no-one knows this more than Kevin Kennedy Ryan, who got married to the love of his life Jessica three years ago.
To reminisce, Kevin, 28, shared a photo of the moment he and his bride were about to have their first kiss as a married couple on Twitter.
However, at the exact same moment the couple shared their sweet smooch, his half-sister Grace fainted and fell face-down on the floor.
Speaking to the Press Association, Kevin, who is originally from Atlanta, US, but now lives in Sheffield in the UK, explained: “It was a sweltering summer’s day in Chicago, must have been 36-38 degrees.
“We’d been out on the lake in the sun all afternoon taking pictures and then the ceremony was at 6pm in this converted loft with giant floor-to-ceiling windows.
“We were all running around so frantically that day that none of us had probably consumed enough food or water, so I think the heat ended up winning the day over my sister’s ability to stay conscious through the ceremony.
“It was immediately after the judge said, ‘You may now kiss the bride’, we were making our first embrace as a married couple and all of a sudden heard a thud.
“It took a moment or two to clock what had happened and then we looked down and saw my sister on the floor. Everyone was stunned, initially we were all scared for her thinking it could be more serious than just a quick fainting.”
As worried guests quickly gathered around her, Kevin said his sister “came back to consciousness within 30 seconds”.
He added: “We were all just glad she was OK.”
Kevin said that Grace was a little flustered and embarrassed, worried that she may have ruined the wedding.
He said: “We assured her she hadn’t and we were all laughing about it 10 minutes later.
“She was absolutely fine once she’d had a sit down and a glass of water.
“We resumed the ceremony – with Grace sitting down this time – and had our first kiss for the second time and then everyone enjoyed the rest of the night.”
Photographer Sean Cook, of Sean Cook Weddings, was on hand to recapture the moment for the second time and Kevin says he and his family cherish both photos.