There is a well-known engineering concept that the more parts a machine or contraption has, the more likely it will be prone to breaking. Same goes for weddings.
Because there is so much potential for something going wrong in a wedding, it’s also likely that the guests will catch wind of it, if not be affected by it. And once they do, you’re sure to hear about it online, like in this AskReddit thread answering the question what’s the worst wedding experience you ever had? And, well, some of them are definitely doozies.

I was supposed to be in the bridal party and was told that things were casual, and to just show up the day of wearing something “dressy casual” I felt good in. I showed up, saw the wedding party in coordinated outfits with their corsages, bouquets, and the whole 9 yards, and realized they hadn’t had the guts to tell me they didn’t want me in the bridal party after all. We took our gift, checked out of the hotel we’d paid for at their specific recommendation (and that they cancelled the shuttle for because “we forgot you were staying there”), and drove 800km back home with our wedding present. I am not friends with any of those people anymore, and thank god.

My sister’s wedding. It was outdoors in South Texas in the summer, and the heat was awful. My sister had picked the venue when it still had water in the ponds, but at the time of her wedding, everything had been drained for repair, so it looked like an old quarry with some mud puddles here and there. The night before, we met at the venue for a rehearsal. My sister decided all the bridesmaids had to wait in the bathroom, but the bathroom smelled like a large dead thing and a lot of poop. One of the girls pulled perfume out of her purse and started spraying it everywhere. I had an asthma attack and was trying to take my inhaler and step out of the awful bathroom for some fresh air. My sister was screaming, “Do you have to f*****g do that now? Can you f*****g process down the f*****g aisle and worry about your f*****g breathing when it’s not my f*****g wedding eve!” Her new in-laws drove me to the ER because my mom refused, because I was being dramatic and trying to steal my sister’s attention on the eve of her big day.

At my rehearsal dinner, my mother planted herself in the middle of the room, sobbing and telling anyone who would listen, (family, friends, wedding party) that I’m making a mistake, my fiance is a loser and the marriage will never work because he’s “low income”. I’ve never been so mortified in my life. Although this is her typical behavior, I guess I thought she’d at least act normal for my wedding events. All my guests left early and after the dinner, I went to their house and FLIPPED OUT. They blamed me for her behavior. 🙄 Typical. The next day my dad called to tell me to beg my mom to come to my wedding because she wasn’t coming after I yelled at her. I told him no. Tell her to stay home. This is my day, not hers. Her attendance isn’t needed. She showed up and told people how she wished I looked as good as her that day 🙄 Sadly this behavior isn’t the worst I’ve received from her. I’ve been no contact for a decade now. And my marriage she claimed wouldn’t last – we’re celebrating our 20 yr anniversary this year. But sadly, people STILL talk about her behavior at my rehearsal dinner.
As mentioned above, the concept of a wedding is complex, no thanks to social, cultural and economic factors (among others). And the more complex a wedding is, the more potential there will be for something to go haywire. Does it have to do that? Not necessarily, but there are some aspects that are common inevitabilities.

My daughter’s wedding. No one showed up to the bachelorette party night before. Groom had the flu day of wedding and was vomiting all over the restroom. Bridesmaid had a seizure during the actual ceremony. Groom’s ex shows up and ruins the first dance. And someone forgot to invite grooms birth mom to the ceremony and she missed it. T O T A L D I S A S T E R Edited to add something else I forgot. The groom didn’t book anywhere to stay the wedding night. When we realized it (the afternoon of the wedding) he opted just to sleep in his mom’s basement. HELL NO. I found them a hotel room.

The bride got chickenpox a week before the wedding and still had her scabby spots the day of. Minister didn’t show up. The whole church waited a half hour before they found out he had forgotten and went out to play golf instead. They got someone else from a church directory who took another twenty minutes to show up. Meanwhile, the groom’s mother was going around giving odds on how long the marriage would last. They’re still happily married 42 years later. Edit: My husband just read this and said “are you nuts? It took more like an hour to figure out the pastor wasn’t coming and at least 45 minutes for the replacement to show up.” In my defense, it was over forty years ago!

On my wedding day my alcoholic MIL got absolutely hammered, fell down stairs and went unconscious and stopped breathing. I was 36 weeks pregnant at this time and had to do CPR. She came around after a few compressions, when the paramedics arrived she verbally abused them. The worst day, still happily married to my beautiful husband though, he’s had a tough childhood as you can imagine.