Joss: "We talked about it. We forced each other to agree that everything was okay, it was the second most lesbian thing we did today."
Harry: "I am not worried about your sexuality, everybody does it. I'm talking about rom-com, basic, normal things. Everybody knows you don't sleep with Meg Ryan or it ruins everything."
Joss: "Well now we do. But how about another lesson you can learn, which is Don't be the boring straight person whose conventional values never bring them any happiness?"
Harry: "Oh I'm sorry, is this what happiness looks like? "
The actual best part gets lost in translation because she's not having the conversation in good faith, so you get stuck in the crossfire, but he says a very true thing, which if I can paraphrase is that in a properly seated equestrian, where you are solid in your saddle, "having values" and "happiness" are the same thing, because they both lead to consistency of character, which is the basis of integrity. You ride your life, your life doesn't ride you: But it starts with not feeling chafed by the rules. Because the rules were developed over thousands and thousands of years, and you're smart enough to know which ones are dumb and which ones are worthwhile, but that is the effort of a lifetime so you need to get started.
And her point is that "values" is a loaded term -- which is true, when you're using them to judge, which he is not -- and that it's all completely subjective, which is false. There's a lot of wiggle room, but not in the way she means, because the way she means is that everything is chaos. And the response to that would be, when you don't know anything, everything is up for debate. And the solution is asking in good faith, "Is this what happiness looks like?" If you draw the line -- using your rational mind and sense of pattern recognition from living in this world exactly as long as everybody else -- to the endpoint of your behavior right now, are you happy at the end of it or not? Because done correctly, at the end of the story everybody is happy. Everybody gets out alive.
And if that's not true, reel it back to today and figure out what strategy you're using and why it doesn't work anymore. Everything is a coping strategy that developed in response to certain stimuli: No kind of crazy didn't start as a solution to a problem. Nobody's born manipulative, we're beaten there. So if that problem is no longer relevant, then you need to drop the tools you built for it and find something new, because that shit rots fast. And in this case, she has a partner in crime: Two people who don't know how to love without being in love, so they have to drop the bomb on themselves to escape. An obsolete strategy, determined to kill something great.