@Render in the older texts, he had concubines, but I strongly believed that was like how Barbossa in PotC always kept fresh fruit on board the Black Pearl despite his curse...being emersed in the Dark Side would typically make Sith Lords less interested in sexual relationships in general, but I think he kept concubines as a way of overcompensating. That said, he was not beyond using the Force to create situations where other people did it. His most powerful ability was mind control, after all.