'A lot of love and a bit of luck': 100 couples on the secret to a happy relationship

But what does it take to stay in love, and what's the secret to a long and happy relationship?

We asked you to share your love stories with us, and more than 100 couples got in touch with the BBC to reveal their romantic insights.

From keeping the fire burning when you live 4,000 miles apart, to "non-negotiables" like always sharing a bed, the results have been fascinating.

Certain phrases popped up repeatedly - including honesty, communication, respect, forgiveness, friendship and laughter.

And the most common pieces of advice? To work through arguments together and be kind.

In honour of St Valentine's Day, here are some of those love stories... and a few of the lessons learned along the way.

'Hard work and commitment'

The night that Mik and John first met, in a German nightclub in September 1978, John was actually on a blind date with someone else.

Mik said she "clocked" John at the bar, "and I thought, yes, I'm going to go out with this guy".

But despite the initial attraction, theirs was a love story that nearly didn't happen.

John's job in the Army took him to Ireland, while Mik remained as an RAF nurse in Germany.

"Probably a year or so into that posting I began to realise the mistake I'd made, so I wrote a letter," said John, aged 70.

Unbeknown to him, Mik's job had also taken her elsewhere but thankfully, her colleagues forwarded his letter.

"It was to be. It was very much set in the stars," said Mik, 69, as the couple celebrate 45 years of marriage.

"What makes success? You need a lot of love. You need a lot of hard work and commitment. But you also need a bit of luck," said John.

'Sort arguments out straight away'

Mair and Alan Hicks, from Swansea, are this year celebrating their 65th year of marriage after joining the same badminton club in the 1950s.

"If you have an argument, sort it out straight away," said Alan, aged 88.

"We've had differences, naturally and, if any couple says they haven't, I'd never believe them."

The couple say that despite "the worrying times", they've shared a wonderful life, including dancing to rock and roll, travelling together and eventually welcoming two daughters.

Mair added: "As long as you're together, you get by, don't you?"

When Cris and Dave met online 25 years ago, civil partnerships and same-sex marriages had not yet been legalised in the United Kingdom.

"We had a period of time where our property was getting vandalised," remembered Dave, aged 54.

"We were in a small valleys town where attitudes were what attitudes were."

He said that when life gets dark and challenging, Cris allows him to vent his frustrations.

"There's empathy there for a start, and there's also then bringing people back to reality," added Cris, aged 59.

"A hug never goes amiss either. A decent cwtch once in a while helps a treat."

This year the couple from south Wales will celebrate 20 years since they entered into their civil partnership.

Cris recalled the moment Dave proposed: "He looked up and said: "I don't want anyone else to have you" and I thought 'ah, sold'."

For Gary and Joy Walters from Caerphilly, 54 years of marriage has taught them one key thing: humour will get you through the tough times.

"Don't get me wrong, we haven't been laughing every day," said Joy, 72.

After meeting at work in a toy factory in Cwmbran in the 1970s, the couple married and went on to have two daughters.

"I believe you must not let arguments brew," said Joy, who also believes that you should always end the day with a kiss.

"And a good sense of humour can work wonders."

'Prioritise each other always'

When Sahir met Dennis more than 20 years ago at a faith event in Cardiff, they had both experienced loss and were navigating life after a divorce.

"It's been a journey and it hasn't always been an easy journey," said Sahir, aged 49, who has recently experienced health complications.

"We've always stuck it out and now I would say we're the strongest we've ever been."

Despite the fact that Dennis had converted to Islam before meeting Sahir, the couple said they were "shunned" by people who did not think their marriage would work.

Sahir explained that with time they have been accepted as a couple, adding that they have "defied all odds and all the naysayers" and will this year celebrate 20 years of marriage.

"I think you have to prioritise each other," said Sahir.

The couple said they had always worked to see past any problems and held on to one another when life has put a strain on their relationship.

"You're always going to love them, but you're not always going to like them," said Sahir.

When Carolyn was walking to meet Carl more than 30 years ago, a construction worker dropped a hammer on her head from a five-story building, resulting in a "lot of blood" and a trip to A&E.

"Most people would normally have a romantic start to their relationship," said Carl, aged 59.

"You having a hammer dropped on your head consolidated the idea to me, actually, I do really love this person. So, yeah, it took a hammer."

The couple, who have three children and live in Blackwood, will this year celebrate 30 years of marriage.

"Love isn't just a nice feeling, it's a decision a lot of the time," added Carl.

The coupled laughed as they explained that each year they have "a professional development review" where they sit and discuss how things are going.

"When we first got married, we decided that we were gonna have some non-negotiables in our marriage," added Carolyn, aged 50.

"We never walk out of the house on an argument. We never sleep in separate beds. We never say the D word... divorce."

'Love is choosing each other every day'

After more than 16 years together, Zafar Khallyev and his wife Dilya currently live thousands of miles apart, on different continents.

"Life has tested us with distance," said Zafar, aged 38.

While he is completing a PhD at Swansea University, Dilya is in their homeland of Uzbekistan with their two children.

He said trust and patience kept them strong.

"And the quiet certainty that love is not about perfect beginnings," he added, "but about choosing each other every day - no matter the distance, no matter the time."