And what if they're both interested in sex, and neither thinks love is involved?
Horniness != evil. Else, we will all be struck by lightning.
You could possibly make the case that sex without love is a form of instinct--a basic, primitive need.
You are kidding, ice, right? Moshe Feldenkrais, who invented the technique of the same name, said that, if the process of walking had as many moral limitations to obey as the process of sex, we would not be able to take a single step. (He was referring to the complex use of different muscle groups for walking, I can only offer the German quote verbatim). Sex like religion is private territory, off limits to the Twisted Rune, the moral majority or everybody else who feels like imposing moral standards on his fellow citizen.
I understand that FR is not about Christianity, Jesus or religion in real life, but I cannot help to feel that Jesus would have other things that would bother him much more in our christian societies than kids born out of wedlock.