Generally I tend to say that crossbreeding doesn’t happen without magic (for example, I once ran a draconic sorcerer who wanted to find a way to continue the magic bloodline without running risk of creating chimeric hybrids that suffered from terrible health problems incurred by hybridizing random species, and his eventual solution was to make a potion that would cause him to only pass on his Sorcery, with the children being the exact same species as the mother).

Adoption is a pretty easy way around that though. A lot of couples DO want kids and that’s fine (especially in fantasy settings where having a large family might just be a lot more normal). And given the levels of carnage that can happen over course of a campaign, there are probably plenty of orphans around from the latest catastrophic event.

Or you can always just get a surrogate.

Honestly depending on the nature of the relationship, if one member is significantly longer-lived than the other and they want to raise a child, then the adoption/surrogate thing might even be chosen over regular crossbreeding just so that the long-life parent doesn’t have to outlive their child.

And hey, if you can’t conceive naturally, you can fuck as recklessly as you like as often as you like