Famed Geldenreichen scholar Polbein the Younger encapsulated romance in Slothjemia with the observation that “That is where the mongrels flourish.” In all likelihood it was intended as an insult and probably as a caution, but Slothjemia takes an almost perverse joy in racial and ethnic intermingling.
In broad terms there are certain races that are more prone to “crossbreeding” and the offspring of these couplings are known widely enough to have their own distinctive labels. These include orogs (hybrids of orc and ogre descent), half-elves (typically a mix of various elven races with humans), and half-orcs (orc and human blend). There are also a number of mixed racial results that thus far defy easy labeling; all manner of combinations among goblinoids (goblins, orcs, ogres, bugbears, jors, and hobgoblins), lizard and reptile people (lizardfolk, kobolds, urds, troglodytes, and draconians), dwarves, elves, gnomes, halflings and humans. Some of these unions are unable to reproduce even if magical aids are employed. Reptilians have radically different biology from everyone else so they are confined to breeding amongst other reptilian people. Elves can’t crossbreed with any full-blooded goblinoids, but half-elves and goblinoids with at least half-human background allow this possibility.
It should be noted that not every romance necessitates reproduction. There are plenty of happy couples that by biology or happenstance are unable to have their own children. Dark elves and goblinoids, for instance, frequently fall for one another (those that lurk about in the dark are bound to stumble into like-minded souls and this can result in unpredictable couplings), but no children will ever result from these unions. Same-sex relationships are also undoubtedly happening, and then there are the illithid that are completely genderless and nobody seems to know what kind of kinky shenanigans those wierdos get up to. The point is that Slothjemia is a place ripe with possibilities.
There are of course notable exceptions. Most everyone knows somebody that will insist their children marry within their own kind. Children who are strong-willed enough, though, will always find ways around family prohibitions. Especially if the child is an adult and the youngest daughter of the Queen. Once that woman sets her sights on somebody, say for example a Fanolanian baron with a penchant for wilderness living, there really is no detering her. The only factor is how quickly said baron realizes the predicament he is in and what steps he takes to accept his fate as a princess’ love interest. Because the only thing more horrific than the oddball mashup couples of Slothjemia is what can happen to a fellow that spurns the attentions of a determined woman. These are the same people that perfected assassination and made combat into an art form. Do you really want to tell her no? Really?