In terms of male human and female human breeding, the discord user Willow is incompatible for any female human ever? This is a common and well understood conception as there are several properties that indicate any attempt of sexual activity towards this human, not only by females but humans of same sex and animals even, are complete impossible.
This particular human has a physique build which is way below the human average which includes muscles, height and of course their genitalia. It is so low it can comfortably sit near the bottom of the list of the most attractive human males, probably too impossible to be in any kind of list as their nano-physique makes them totally invisible by the naked eye at all times, not to mention their horrendous odor. This is caused by the term "never hit the gym" and "showering once per week" which is highly believed it is the root of this situation.
Also we can mention this human almost completely lacks social skills which is the main component to attract a mate in the first place. Their sociability is dangerously low to the point their whole nervous system encounters a whole breakdown whenever they try to interact with any human outside of their bloodline. This has caused this user to fall to a terminal condition known as "depression" which constantly terminates their nervous cells and decreases their sanity at an exponential rate, making them what it is known as "retarded". This has led them to be attracted to 2-Dimensional Drawn Underage Girls or lolis which is another major property that greatly supports the main idea.
A great fun fact, this human also plays video games such as Pokemon and Blue Archive which completely seals the point.