That's one of the biggest lies we tell ourselves and our spouses. And a lie is a lie, no matter how small.
And big lies, like cheating or hiding debt, aren't the only way to destroy trust in a relationship. A 'little' lie about being fine when you aren't may take longer, but it is just as devastating to a relationship over time.
I took time to think about why I said I was fine when I wasn't. I lied because it felt safer. I lied because I didn't always believe Mark would care that I was hurting or mad.
I don't tell Mark I'm fine when I'm not anymore. I tell him I'm frustrated or annoyed or disappointed or really sad. He doesn't always like to hear those things, but he appreciates being told the truth upfront instead of getting hit with it out of nowhere a couple of hours later.
Figure out why you hide behind 'fine' and then commit to being honest and taking care of the trust that glues you together.