This is a problem all around.
The no intermarriage thing with Khajiit and wood elves is more than an oversight, especially when you see a wood elf in Riften explicity married to a human. (In fact, there is also an example of a high elf married to a human and historical examples of marriages to dark elves in the lore, and, let's be honest, dark elves aren't that picky.) Even argonians are marriageable, which kills the 'no furries' excuse some have jokingly put out (sorry guys, but furries aren't only fur covered. And marrying a werewolf is allowed and that can get pretty hairy. Pun intended.

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It's even worse when you can't marry a character of your own race. (For example, there are NO redguard males who are eligible, which is ridiculous.) No Khajiit might be excusable if you're playing a Nord, but what about other races? No intermarriage, really? Hm. The only way to justify it is to say that every other Khajiit is extremely attached to their religion and refuse to be married by Maramal -- same for wood elves. But argonians also have their own religion and marriage ceremonies, so...what gives?
The only rationalization I can think of is that Khajiit (along with the wood and high elves with one -- count it, ONE -- exception) are part of the Dominion and refuse to marry those who aren't part of it. But that isn't given in game, so it all amounts to a big fat gap in the lore.