The idea that finding "that special someone" is a convenient story deliberately perpetuated to keep people content with their misery, telling them that eventually they'll find bliss and that life only seems like crap because they don't have it yet. "Just stick with your crappy job, pay your taxes, and keep the gun out of your mouth and you'll be rewarded and everything you've suffered for will be worth it, because there's someone out there for everyone, and you can't prove me wrong". Y'know, kinda like the promise of heaven.
Relationships and sex are just the opiate of the masses, and often go hand-in-hand with religion. I know of very few people that are genuinely happy in relationships, the rest just confuse their new, overwhelming feelings for happiness and fulfillment. Going through people one by one, trying to find that mythical "special someone" through trial and error with only a tenuous grasp of probability is setting yourself up for a world of hurt, which usually leads to trying to find happiness in severe compromise (i.e. well, at least you're not as bad as the last few, and I can tolerate you, so let's get married). Plus, the excessive hygiene and ridiculous amounts of interpersonal maintenance are a real drag. Besides, sex is an incredibly mild and watered-down high that is a million times more dangerous and risky than a spliff, and about half as enjoyable.
tl;dr focus on enjoying your life instead of being told what you need in order to be happy.
