It is in principle possible to find someone who holds the ideally matched set of opinions persistently

It's easier (though still non-trivial) to find a set of someones, each of whom holds matching views on some subset of the relevant opinions, and who together cover most or all relevant opinions. It's not easy to find people with whom you match thusly!

Finding good, true friends is not something that just happens trivially. But it's worth it. I wouldn't want to settle for less.

Is my reasoning flawed, or is this a matter of you experiencing the latter effect (suspension of disbelief) more strongly?

If I'm interpreting your phrasing correctly, then... um, yes. It's a matter of that. I value truth, and honesty. If I know someone is lying to me, I'm not just going to "suspend disbelief" and pretend I don't know they're lying. Not to mention: how am I going to get around the fact that their lies and deceptions make it very difficult for me to respect them? More pretending? More self-deception?

No thank you.

Finally:

If brutal honesty satisfied all human emotional needs the world would look very different than it does.

Who said honesty has to be brutal? The truth may be, but its telling may not. And I am not comforted by lies.