According to your religion you should not have sex for pleasure , whoever you have sex with ,or that's called luxury. The only purpose of sex is procreation. So there is no value in sex other than making children , and if you are doing it for pleasure it is a sin. ( i dont mind what you are doing , that's just what the catholic church says ).
That's actually a common misconception. The church teaches that for sex to "whole" it has to have both the formative (pleasure/love) aspect as well as the procreation aspect. You can certainly procreate outside of marriage (in the literal sense. This is also why they teach against birth control even for married couples. Only in marriage, with the purpose of child bearing is sex "whole".