With 47 per cent of married couples divorcing, despite the optimism and strength of feeling felt in those first few years, 'till death do us part' is not a guarantee.The five grounds for divorce are adultery, unreasonable behaviour, desertion, if you have lived apart for two or more years and if you've lived apart for five or more years.
While there's a requirement to cite at least one, the legal terminology can only convey so much.
Were their shifts and signs pointing at trouble ahead? Or is hindsight twenty-twenty vision? Did those closest to you foresee heartache? And what about the play you yourself played - how did your behaviour impact the relationship?
It's not always as simple as ticking a box, but as these Reddit users point out, there are signs - sometimes very early on - that a marriage isn't working.
1. The canoe test
Redditor stoopidquestions asked a question to which there is no easy answer: "do you tell friends when you realize their marriage is doomed?"
"We went canoeing with a recently engaged couple and not ten feet from pushing off they had already flipped the canoe and were yelling at each other. These were both avid outdoorsy people.
"They were both miserable the rest of the trip. At that point we knew they just weren't right for each other. Their marriage wasn't ever all that happy, yet lasted five years.
"I really think the canoe-test is a good way to judge a relationship; how well you work together and how you handle inevitable disaster."
2. Wedding day clouds
Heartbreakingly, pinkyogurt12 saw a side to her husband on their wedding day which signalled the beginning of the end.
"I got married at the courthouse downtown. Immediately after signing the papers and being pronounced married, we walked outside to leave.
"My new husband spent the next hour and a half talking to his buddy and texting while I walked behind them. They then dropped me off at home and left. It didn't last long."
3. Bad language
It wasn't until Illah got divorced that he gained a certain amount of hindsight on how it's OK to yell and fight, but the wording is key.
"What's poisonous is contempt and resentment. When you disagree, do you discuss the issue or the person? Is it, 'I want sushi, but you want pizza' or is it, 'You always want sushi, I never get pizza.'
"Subtle difference, but those little things are so much more important than most people realise.
"The latter phrase shows the person is the problem, uses absolute always / never language which pushes the other away, shows that someone is 'keeping score' and thus not letting go of negative feelings (resentment), and a sense of blaming the partner for 'causing' the pain and disregard for the partner's desires (contempt)."
"Once the problem is your partner rather than the situation / issue / disagreement etc then you're on the road to unhappiness - no matter how you slice it."
4. Different sex expectations
Professor D described the how he and is ex-wife had different needs from their sex life, which became a problem.
"When I said sex once a month wasn't enough for me and she said: 'Yes, it is.'
"We even went to pre-marriage counseling and it was discussed there. We had discussed and agreed that sex on a regular basis was necessary. For her, once a month IS a regular basis.
"She was under the impression frequent sex was for newlyweds, so at counseling she thought we were talking about newlywed issues."
5. When they behave like this
"I look back and realize that he scared me even in the beginning. A week before our wedding he flipped out on me in the parking lot of a hotel that one of his groomsmen was staying at. They called the cops and everything.
"Fast forward to married life and he was verbally abusive and isolating. Later it progressed to financially restricting me (I was a waitress and he cleaned out my pockets daily after work). He never allowed me to call home to my family and I wasn't allowed to have friends." - gngrvxn
Sometimes there's no telling
However, in spite of all the hints and signs other spouses detected, sometimes we're completely blindsided, as bac0nb0y explains.
"Going into the marriage, I knew that we would be together forever.
"I thought we had a very solid support structure and knew I would love her the rest of my life. We fought occasionally, but we're both headstrong.
"The first week of December in 2011 she told me she wasn't happy.
"The second week she told me she didn't love me anymore.
"The first week of January she wanted to separate, and at this point we're moving toward a divorce.
There were no signs that my marriage wouldn't last; she was telling me she loved me and how amazing I was a few days before she told me she was unhappy and might not love me.
"I still don't honestly understand what happened between the two of us, but I know that I haven't changed. Maybe that's the problem, maybe what she wanted changed. I have no idea".