There is a place for sexual expression in loving relationships.  That expression doesn't have to be "resisted" where there is love and commitment, unless 
*you are a woman who has been told that a pregnancy will kill her
*you are in school and need time to finish school and get established in a career before having children
*you already have all the children you can afford to raise 
And, with respect to the above * items you refuse to use effective contraceptives or just go ahead and get sterilized.  

Sex is not just for procreation.  That is the problem with the way the Church looks at sex and teaches about sex.