Lies damage relationships. How that damage happens depends not on whether it's big or little lies but rather who the lies are told to.
Among the many horror stories I can tell you about my mother-in-law, one trait that stands out are the lies. Although at one point she had a reputation of "just tellin' the plain truth", the reality is that even then, there was enough of a lie embedded to make her truths dangerous.
Her plain truth was coated with a thick layer of southern charm, which made it more believable to some people.
She inflicted massive damage on others by carefully telling lies disguised as plain truths to key people in positions of influence. At times I thought she would have made a great politician with how she did that. Since she was a mayor's daughter, perhaps she learned that bad habit growing up.
Since she was my mother-in-law, I wanted to believe her, but found I couldn't.
After discovering her true nature, I found myself double-checking just about everything she told me. I learned to ignore half of it and to take the other half with a grain of salt.
When neighbors made her cookies, she threw them out without a taste. When the neighbors later asked her if she like them, she smiled and responded "I loved them!" completing the gesture with a gentle clasping of her hands together giving an expression of sincerity.
I only discovered her true nature and the extent of lies when she lived with us. You learn a great deal about people when you live with them. The lesson I learned with her was that believability is an important part of trust.
Although her actions made her believable to others, I knew better. What she did told me more about what to believe than anything she said.
Cheaters come across as very sincere and believable. When you're hurting, you want to believe in their sincerity. When they are your spouse, they are in a position where you feel compelled to believe what they tell you. They use their position to take advantage of you.
If your test of whether or not someone is trustable consists only of their believability, you are headed for a shipwreck. This is only one part of what constitutes trust. Believability and the other components of trust can all be exploited. It's only when you have the whole trust formula that you know whether or not you can really trust your spouse.
I lay out the trust formula and all the building blocks of trust in my video "How Can I Trust You Again?" You will be able to see what is missing and what needs to be worked on in your marriage. Rather than have to double check and doubt everything you're told, you can know better ways of knowing what's trust worthy and who is trust worthy.