Women’s sexual preferences change over the course of their menstrual cycle, with partnered women being most attracted to single men during their fertile stage, according to a new study.

Researchers at the University of Padua in Italy suggest that partnered women, who want to have an affair or even think about having a fling, subconsciously choose single men when they are fertile. On the other hand, their attraction shifts to coupled men when they become infertile.