A third of people in long-term relationships in the UK have remained together despite one or both parties being unfaithful.

In a new large-scale survey of the state of Britain’s relationships, 33 per cent of respondents said they and their partner had ‘survived’ some degree of infidelity, whether that was emotional or physical. 

Despite 80 per cent of us saying we would end things if our partner cheated, almost one in ten relationships had survived a one-off incident of sexual intercourse or a sexual act, and 8 per cent had survived repeated incidents.

The most common type of cheating was emotional (in 12 per cent of couples), closely followed by kissing another person (11 per cent) and digital infidelity via a chatroom or ‘sexting’ (11 per cent). 

[Read more: This Is Why People In Happy Relationships Still Cheat]

The survey, commissioned by the relationship charity, Relate, asked 2000 people about the state of their relationship with their significant other and found the high rates of infidelity within partnerships.

Relate counsellor, Rachel Davies says: “As a society, we’re pretty unforgiving of cheating – our research found that the vast majority of people said they would end the relationship if their partner cheated. However, we know that in reality many couples are affected by infidelity at some point in their relationship, and that many choose to remain together after it happens.

“What constitutes infidelity can vary between people, for example some people may think that sending flirty texts or messaging someone online is infidelity while another person would think its fine as long as you weren’t having a sexual relationship with someone else. What we see is the damage done when one person feels they have been cheated on regardless of what form that cheating takes. A betrayal of trust can leave people suspicious and doubting – and this can be difficult to turn around,” says Davies.

Perhaps unsurprisingly, given the high rates of bed-hopping going on, 30 per cent of us who have been in a relationship with a partner less than a decade have doubts about whether it will go the distance.

Despite this, millennials do largely still aspire to have a ‘relationship for life’. Whether this is marriage or a different type of partnership, a resounding 87 per cent of 16- to 34-year-olds said they did want to have this with someone.

Flying in the face of high divorce rates (42 per cent of marriages end this way), millennials remain optimistic about a love for a lifetime. And 85 per cent think they will meet that person in their twenties.

Although most of us seem keen on a committed relationship, we’re less keen to work at it: 43 per cent of men and 33 per cent of women said that if you have to work at a partnership then you aren’t right for each other. Those who’d been in a relationship less than ten years were more likely to hold this view.

Relate Counsellor Dee Holmes says: “Having been a relationship counsellor for several years and in my own relationship for 35, I know that long-lasting and fulfilling relationships don’t just happen – they require hard work, humour, and may benefit from support such as counselling during tough times.”

How can you move on after being cheated on? 

Davies says: “If you’re affected by infidelity it can be really beneficial to seek the support of a counsellor. They can help you to work out what it was that led this to happen and whether there may be issues in the relationship which contributed to this happening.

“For the person who has cheated, they need to be able to accept responsibility for what happened and work out the reason (not the excuse) for it happening. The hard part is often getting the other person to also realise how their actions or behaviour may have also contributed to the situation that led the cheating to happen.

“It takes hard work on both sides but if you’re both committed and are willing to be open and honest with each other, it is certainly possible to move on from infidelity and even to come out stronger as a couple. Going forward, it’s probably helpful to set clear boundaries around fidelity so that you both know what’s acceptable to you and what isn’t, it’s important to understand what your partner needs from you in order to feel they can trust.

“Whilst there should be no shame in choosing to stay, you need to be kind to yourself and especially if your partner cheats repeatedly and does not appear to regret their actions, you may want to consider if this is the right relationship.”

Believing we don’t need to work at relationships (and that everything should fall together perfectly) might not just the naivety of youth, but the result of social media – 51 per cent said that they make it appear to others that their relationship is happier than it really is when online. 

And it isn’t just young people falling into this trap: 29 per cent of the general public say they are posting on Facebook and Instagram to portray a reality that might not exist behind closed doors.

But it seems we’re tiring of this perfect relationship façade – the vast majority of people surveyed (92 per cent) feel people would benefit from being more open with each other about their relationship issues.

Holmes says: “We’d probably all benefit from being more open and honest with each other about our relationships and realising that nobody’s perfect, however it may seem on the surface.”