Someone who is fundamentally honest doesn’t necessarily say what’s on their mind continuously (and who would have time for that?!), but doesn’t say meaningful false things.
Also, the idea that everyone you call a friend is 100% loyal is not at all something you should believe or pretend to believe. Your relationships shouldn’t be based on it. You don’t have to live like that.
"A lot of science fiction plots and comedies spell out what would happen in a world when people were completely honest. You might think, that would be great, no more hypocrisy and shilly-shallying and beating around the bush. But actually, as these comedies play out, this would be a nightmare. We don't want to live in a world in which everyone is completely honest. The reason is that our relationships depend on certain understandings that, when it comes down to it, are fictions. Like that two friends are completely loyal to each other and instantly generous. That couples are faithful, not just in action, but in thoughts. Now, we know that these are not quite reality, but still, we don't know that the other person knows that we know that they know. And that's what allows us to preserve the relationship. If everyone were to say what was on their mind at every time, who they fantasized having sex with, who they fantasized killing or harming, that would pollute the pool of assumptions that allows us to get along."