A romantic kiss is, of course, a sign of love, but also a complex exchange of information, consisting of biochemical and bodily signals. A kiss (especially the first one) is, first of all, a kind of compatibility test that can instantly cast doubt on the emerging union.
In addition, American psychologists Susan M. Hughes, Marissa A. Harrison and Gordon G. Gallup Jr. from the University of Albany (USA) found that men most often kiss their partner to get her sexual favor or to make up with her after a quarrel. Women, on the other hand, use a kiss to make the relationship stronger and to make sure that the partner is still attached to them.