If any doubts do arise, most people will talk them through with their partner, and aim to have everything resolved by the big day.
However, some people wait until far too late to bring up their grievances - as a recent Reddit thread has revealed.
When asked 'Redditors who have left your fiance at the altar, why did you do it and what happened?', hundreds of users came forward to share their stories, and some of them will definitely shock you...
Because he was sleeping with someone else'Ten days before the wedding I found out he was sleeping with someone else. Took me two days to decide not to get married.'
'Then over the next three weeks I discovered he was a sex addict and had been seeing other people for the entire nine years we were together. Got reeeeeaaal close to being stuck in that nightmare. Thankful every day that I didn't go through with it.'
Because she was sleeping with someone else'This happened to a previous work colleague. I had been working with him as a cleaner for 4 years and he had been with his then partner for a while. Everything seemed hunky dory and soon enough he proposed to her and she accepted.'
'As the wedding day approaches, I arrive at work to find out from my boss that the wedding has been called off. Apparently his fiancée was a lesbian and had been cheating on him for a while. What I never understood is how she could accept the proposal, surely when he was down on one knee hat would have been the ideal time to express how you really feel.'
Because she was too controlling'I left my ex-fiancé a month before the wedding. I never actually proposed to her, she more or less did it to me. We were in a mall and she wanted to go to a jewellery store to look at engagement rings. I wasn't expecting to walk out of there with one but we did. The salesperson even took a 'just engaged' Polaroid.'
'She became more and more controlling and I couldn't take it anymore. After I left her, her friend texted me on the day of the supposed ceremony telling me the cake was delicious. My ex somehow managed to break into my email and asked me who a girl was in an email I received AFTER I left her. I could understand her reasoning if it was before, but it wasn't. She also texted me a while after I left and told me she missed her period. An hour later, I got another text that said, "Never mind." I'm pretty sure I dodged a bullet by leaving.'
Because he needed three attempts'My uncle panicked and fled his wedding before the ceremony. He made it a couple states away, hid from her and eventually patched things up with his bride-to-be. They scheduled a new wedding, at which point basically the whole cycle repeated itself.'
'On the third wedding they actually got married and over the next year had a kid and then split up for good. He still hangs around his former in-laws and hates her second husband (her husband of like 20+ years now).'
Because she didn't really love him'I left a man at the altar. I was in my dress and getting ready to go to the chapel, when I realized I couldn't. I froze. I didn't love him as much as I craved the safety and security that being married would bring.'
'I was fairly recently divorced and very young and scared. He eventually found a lovely woman and they are very happy together. I don't think either of us would have had that with each other.'
Because his friends held an intervention'A guy I knew did this. He was a nice, laid back guy marrying a toxic person. I can't get into the details because I didn't know him too well, but apparently his friends had been telling him to break it off from the beginning. They had a final intervention for him the morning of the wedding and they finally convinced him to just leave.'
'He showed up at this festival I was at during what was supposed to be his wedding. I saw him and said "Hey man, aren't you getting married today?" and he had this kind of faraway look and said "Yeah, that's not happening anymore."'
Because she didn't want to commit, and he did'Not at the altar, but I bailed just two days before we were headed to city hall. It was a green card marriage. On our second date she mentioned that her visa was expiring in six months, and I jokingly proposed to her. We continued dating, were falling for each other, and that proposal became much more real as the deadline approached.'
'I backed out at the last minute because we just didn't agree on a few details. Living arrangements and finances were easy. What couldn't be negotiated was how seriously either of us wanted to take those vows. I wanted to at least attempt to be a married, monogamous couple. She didn't really want to commit to that. If she falls deeper in love, great. If not, we're just roommates. I miss her, but I think I dodged a bullet. I believe she would have vanished on me at some point, and I could be in a real jam over immigration crime.'
Because he got wasted at the rehearsal dinner'Not me, but a friend just cancelled her wedding on the day of. I guess she'd been having doubts for awhile but kept hoping things would get better/ had already spent so much money, etc.'
'But at the rehearsal dinner her fiancé got wasted and was being an embarrassing asshole and she just couldn't take it anymore. Called her mom first thing in the morning and told her she couldn't go through with it.'
Because all she cared about was the wedding'My brother left his fiance a week before the wedding. Basically as soon as he proposed, all she cared about was the wedding. He wanted a very small wedding and she wanted a huge one. She was also VERY religious (her father is a preacher) and he was not at all.'
'She told him she wanted him to become a deacon in her fathers church - and he told her no, he didn't want to do that. Pretty much they were disagreeing on everything up to that point. Finally he called it off. He said it was the hardest thing he's ever had to do but he knew he made the right decision. '
Because it was all too quick (but there's still a happy ending)'I called my wedding off with 10 days to go because I felt I was being pushed into it. My girlfriend, who I loved and who loved me, got the wedding bug and her and her Mum sped through the set-up in record time with everyone assuming I was fine with it. I ended up freaking out because I didn't feel ready to do it and pulled the plug. We split up, she moved out and we were both miserable.'
'We started talking, got back together after a couple of months and a few years later we've rebuilt everything, we're engaged, buying a house and I couldn't be happier. I wish it hadn't happened but I'm pleased I didn't get married against my wishes. I think it would always have been in the back of my mind that I didn't really want to do it whereas now I'm sure.'
Because he already had a wife'Wasn't me personally but... "If anyone here has any objection, speak now or forever hold your peace" Woman in the back stands up and says "the groom can't get married as he is my husband".'
'Turns out the woman who objected and the groom were in fact married and tried to get divorced, but the divorce was never completed. So technically the groom was still married and the wedding did not proceed.'