They are condemned by society, ridiculed, shunned and isolated, effectively ex-communicated. Partly to avoid these sanctions and partly to enjoy the warmth provided by conformity and acceptance, couples marry. Today, a myriad of lifestyles is on offer. The old fashioned, nuclear marriage is one of many variants. Children are reared by single parents.
Homosexual couples abound.
Formed by adults in search of sources of long-term and stable support, emotional warmth, empathy, care, good advice and intimacy. The members of these couples tend to define themselves as each other's best friends. It is folk wisdom to state that the first three types of dyad arrangements suffer from instability. Sexual attraction wanes and is replaced by sexual attrition in most cases. Economics are not sufficient grounds for a lasting relationship, either.