Express your opinion on the purpose of sex in a relationship or between two people.
Sex is not an expression of affection; it is an expression of lust, a culmination of feeling aroused by the presence/actions of another.  I don't have sex to express affection to another person; I have sex because I am aroused by that person.  No one thinks, "Gosh, she is such a nice person that I think I will make her day and stick my penis in her."