Reading that closely resembled the pain I felt when I read the red wedding chapter. George please save Dany from this murderous child molester
Sadly it does relate to marriage. Not only does it relate to marriage, it relates to love (hence why hizzy isn't shown). There was 3 sets of three different visions that the undying showed Dany. "daughter of death", "bride of fire", "slayer of lies". In the "bride of fire" section it showed her silver in a setting that resembled the place she lost her maidenhood to Drogo (representing her marriage to Drogo), the next showed Aeron dead at the prow of Silence (which I guess represents her marriage to Euron... I really don't know at this point), and the last one showed a blue rose growing from a chink of ice (confirming R+L=J, and representing her marriage to Jon... I guess).
Like I said, Hizdhar isn't there because it's "bride of fire". There's no fire (love) in their relationship.
And as for the thing with the dwarfs. In Dany's vision it represented the war of the five kings (5 dwarfs abusing a beautiful woman - westeros), in Aeron's there are more dwarfs. My guess being more kings and queens have risen, or rising up since dany was in the HOTU. Which was something Mel warned Stannis about, that more pretenders would rise, or something.