An escort is the person with whom you came to a dance or to a dinner with.
It is often expected that whoever your escort was when you arrived will also be your escort when you depart.
Most often, a person's escort is his or her spouse.
It is assumed that if spouses or loved ones were interested in primarily talking to one another,
they would have stayed home together rather than come to a dinner or a dance.
After all, the point of going to a dinner or dance is to socialise with others.
This means dancing and talking with a number of people, and not a select few, and never a select one.
At a dinner party, one never sits by his or her escort.
Likewise, usually only the first and the last dance of the night should be danced with one's escort.