One secret can be enough to end a long-term relationship if it causes enough damage and hurt.
A woman has been left distraught after accidentally finding a "shocking discovery" on her partner's phone, that unearthed a five-year affair with his ex-girlfriend.
The 55-year-old lady was on holiday with her 70-year-old boyfriend when her mobile broke and she used his to keep in touch with friends and family.
But it all came crashing down when she spotted a recent conversation between him and his ex on WhatsApp.
She sees it as an "absolutely staggering betrayal" and cannot eat or sleep as she ponders whether to stick by his side.
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In her post on Mumsnet, the woman explained that her boyfriend of 10 years had a "very romantic and passionate" relationship with his prior girlfriend.
"She finished with him when he was still very much in love with her and he immediately joined a dating site and met me a month later," the woman said.
Whenever she has asked her boyfriend about his ex, he said they aren't in touch and his "philosophy is to move forward in life" - which is now evidently a lie.
Describing their current relationship, she explained: "He's super committed, affectionate, great with my two kids, supported me through breast cancer, bereavement, family difficulties, has been my rock, my source of safety and comfort.
"If anything, he's been too needy and suffocating and has always wanted to push the relationship on faster than I've been comfortable with."
The secret messages have had a huge impact on the woman's confidence, explaining further that her senior boyfriend has had "pretty bad erectile dysfunction" since the beginning of their relationship.
"Maybe she was the last woman he could sustain an erection with? It makes me feel extra unattractive that he can barely get it up with me," she said.
Since unearthing his affair, the woman has pretended to have heatstroke on holiday to avoid him and has been prescribed sleeping pills as she struggles to rest.
In the five-year exchange, there has been a lot of messages "reminiscing about the past in a normal way", but he tells her that she will always be his sexiest woman and she replies "and you my best lover".
Though they acknowledge they are "friends", he calls her "sweetheart" and told her she was "fit in every sense of the word".
"The worst thing, though, is what is missing from the messages, which is ANY mention of me!" the woman added.
Whilst it doesn't seem as though they have met up, "the intention was clearly there" and she doesn't think she'll be able to trust him again.
The woman is torn over whether to confront him, try and rebuild their relationship or break things off.
Fellow Mumsnet users encouraged her to leave him after "all the deception".
One person said: "I don't think I'd be able to get over something that's happened over such a long period of time - it's not just a moment of madness is it. She's constantly in his thoughts."
A second agreed: "How are you going to grow stronger as a couple when you know he's in love with someone else?
"It sounds like you've allowed yourself to become very dependent on him, but you have survived so much and you can get through this.
"Get a handy man, get some hobbies, make some friends and start putting yourself first. Thank god you haven't married him."
A third wrote: "He doesn't deserve you and you don't deserve to be second best."
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