There's a substantial minority in the community that dislikes the Litany of Gendlin, so you have plenty of company here.
But even granting the premise that believing true things conflicts with being happy, believing true things has been useful for achieving every other type of goal. So it seems like you are endorsing trading off achievement of other goals in order to maximize happiness. Without challenging your decision to adopt particular terminal values, I am unsure if your chosen tradeoff is sustainable.
I'm not endorsing that, for exactly the reason you said: knowing stuff, on average, will let you achieve your goals. The original quote, though, stated that the truth is "never unsatisfying", which seemed to me to be a false statement.
Here's the new thread for posting quotes, with the usual rules: