It's how things work

Evolution has programmed us to like what we like and has a reason for so. The survival of the species depends on it. For giraffes, it is important to find out whether a female is ready to mate before attempting to do so. The way a male does this, however, is not appealing – he drinks her urine. Once he knows she is ready, he may need to fight off competition, which he does by swinging his long neck at the other suitor.

Humans are a bit more civilized in procreating. But, because we have evolved many different ways of getting the job done, sometimes the functioning gets a bit absurd. Wanting to procreate with someone who cannot yet do so is counter-productive. For me, even knowing that my lover is incapable of having progeny does not prevent me from desiring Her intensely.

Love, the impetus for procreation, comes in many strange forms and is a many splendored thing. Your biology has an imperative that is forcing you to mate. Your way.