My personal experience is that the men I've been with have always had a harder time I explored love with others than I have had when they did the same. I'm not going to generalize to say that men are hardwired against polyamory, because my sample size is miniscule compared to the billions of men alive. But I will say that I have only had experiences where the men struggled more than I did. (Maybe that will change!
I believe it may
be true that women are more likely to want security and stability. Most (but not all) of the women I know want that. But many of those women are still poly and enjoy being poly.