Bear sex is one thing but if you had halflings that are say dnd movie style, just scaled down humans, you open a whole other can of worms. Though I suppose they could just block romances for short races instead.
Okay, I'm going to call time on this comparison, which keeps coming up. At least it feels that way, and frankly I find it massively uncomfortable to think of sex with short adults in any way analagous to sex with children, which I assume is the "can of worms" referred to. It's not, and I'd not be surprised if real life short people found the comparison deeply offensive.
Let's just not go there again.
In fact, if we can go a few days, or even longer, without any sort of implicit or explicit reference to sex with children in any context on these forums, I'm sure many of us will feel more at ease.