A love seat is a piece of furniture that's large enough for two people to sit on. You don't have to be in love to sit in a love seat, but you must be prepared to share a small space with someone else.
The very first love seats, in the 18th century, were made to accommodate just one woman and her voluminous 18th century skirts. During the 1800s, love seats were designed to curve inward, so two people could sit almost facing each other. This was also when the small couches began to be thought of as an aid to courtship, a sofa built for two.