Ultimately the movie reinforces the idea that being in a relationship is the key to happiness -- an iffy message at best. Many different types of relationships are portrayed, with different levels of happiness.
Couples yell in a few scenes; in a fit of rage, a woman throws a mirror on the floor and breaks it.
Couples kiss, make out, and discuss sex. A woman disrobes off-camera and jumps into the water to skinny dip after she propositions a married man, though viewers don't actually see any sensitive body parts. A couple kisses and fondles each other in an office; later, a woman straddles a man in the same office and they presumably make love (but it's not shown).
Language includes several "s--t"s, a couple of uses of "f--k," "suck," "ass," "bullsh--t," "a--holes," "boobs," "dick," and "oh my God."
Brands/logos for cigarettes (American Spirit is particularly prominent), beer, and a few other products (Crest WhiteStrips) are shown. The movie is based on a popular self-help book by the same name.
Drinking, Drugs & Smoking
One character lies about smoking in secret; some casual/social drinking and smoking at parties, restaurants, and bars.