Inuyasha is actually trans species. and there fore we have to convert the 300 year (his cat years) into human years then he is actually 62 and if we convert her human years to cat years then she is 72. there fore The girl is actually older then the cat eared demon and as such since they have a 10 year difference in age the relationship is perfectly acceptable and if i wanna stick my dick in a blender to pictures of old ladies fucking cats then there is nothing wrong with that.

here is the resource used to make my calculations https://www.almanac.com/cat-age-chart-cat-years-human-years