Why YA and Teen cant have romantic interactions?

I think that was the only issue with how it worked, but I believe that was only set out that way because of the fact the game needs to not allow ANY romantic relationship between a young adult and a teenager, to due massive legal reasons. Which I would defend, and it, luckily, isn't exactly difficult to raise romantic relationship again when the second becomes a young adult (get your sim flirty and it only takes several hours to get to a point where woohoo is possible.