It's ridiculous full stop. 5'9 is the average male height in the USA and UK lol. I'm 5'11 which is way over the female average, so it's quite predictable that my boyfriend is shorter than me. The idea that a man should be taller than his female partner is literally just a societal construct based on the fact that on average, men are taller. Not a good reason to date or not date anyone, in my opinion!