Parties are particularly good occasions to begin semi-illicit friendships and relationships. They generally begin with the men and women sitting shyly apart in small clusters in opposing sides of the room, and only when dancing begins, or when the noise level is so high to lend a modicum of privacy to the conversations that the furtive tentative exchanges begin. The girl looks up at the man through her lashes, tries hard not to stare into his eyes yet at the same time she appears to look wholly focused on the man and the conversation. The guy blocks out the rest of the crowd, physically turning his back on it, in a sense making an aegis of his body to protect the girl from view. If the conversation ends fortuitously, phone numbers are exchanged privately and away from the others' curious eyes, and from there a relationship begins.
Universities are another great place to meet a member of the opposite sex.
I have also heard of relationships beginning when a persistent girl discovers a boy's name and his phone number and the relationship begins on the phone. There are endless phone calls where an anonymous caller plays music for the called, or simply hangs up when someone answers the phone whom the caller does not desire. Many conversations begin this way. I have not dared ask this very sensitive question from even the closest cousin. Films and books all are unforgiving of women.