Sexpologies are most commonly used when dealing with ex-boyfriends and/or ex-girlfriends. Sometimes you've apologized so many times there just isn't anything else to do except give them a nice, big sexpology.
Jim: "Hey man, your girlfriend every forgive you for not coming home until really late again this weekend?"
Eric: "Yeah... I just gave her an all night sexpology and promised never to stay out late without calling her first again. We're golden."