Animals such as cats and rabbits run on mere instincts whenever a possible mate might be within range during the season, then others such as penguins mate for life and never switch, change or substitute. We human beings have the ability to go beyond either of those so we do not end up with uncontrollable, illicit scenes in parking lots, so the challenge is to sort the emotions and such in relation to our various types of relationships -- acquaintances, neighbors, friends, family, intimate companions and so on -- responsibly (without causing inter-relationship conflicts) rather than just doing whatever we think might feel good at the expense of someone else who would be affected.