You're putting words in my mouth.  

I have sex with my wife because we both enjoy it, because we are husband and wife (and like one another), and because it's a pleasurable act that men and women are designed to do.  I do not have sex with her to express my love for her (I do that in many non-sexual ways), and, yes, sometimes she enjoys it and sometimes she does not but does it because it relieves my sexual urge.

Last night my wife had to work late, and I offered to make dinner.  That was a true expression of love, more loving than any sexual encounter could ever be.