Board Thread:General Discussion/@comment-19365920-20131109125448/@comment-5569775-20160624090201

@80.94.160.227: You missed the point of the thread a bit. It's not about interracial(which is in the game as a male Khajiit can marry a female Dunmer or a male Dunmer can marry a female Argonian, both because of certain books), but rather that Khajiit can't marry Khajiit and Bosmer can't marry Bosmer, as well as those 2 lacking a marriageable person of either gender.

Also, it was probably excluded due to them rushing the game. And they didn't fix it with a patch because either it was more work than they wanted, or like Kiadony said, they lacked the recorded dialog.