It is a good point initially, but the more you think about it, the more it falls apart. The gender of the wolf doesn't fundamentally alter MC's power to summon a wolf. It is just a funny little detail, serving the interests of the wolves more than their master and mistress. We may find out more as he accumulates more powers if they are more drastically altered, but allow me to posit this: perhaps Meri is lying about her powers in the first place, and she has the same power he does to attract partners to steal their powers. Based on what Naveen said, they have powers that function much the same in that regard. It would be amusing to find later on in the VN that Meri is his archenemy, a final boss with all the powers of the people that she fucked.