Board Thread:New on ALDNOAH.ZERO Wiki/@comment-5858837-20150218002754/@comment-25450485-20150310210827

It is simple:

Before the assassination: Slaine was the main candidate, but couldn't confess his feelings since their positions were vastly different (and Cruhteo would've probably killed him if he had a romantic relationship with the princess).

After the assassination and before the reunion: Asseylum misses him and greatly values him as a friend. He was still in the friendzone then. She starts to develop feelings for Inaho.

After the reunion: Asseylum was gravely injured and was being taken care of on the moon base in secret. But the war and him being with Saazbaum has changed Slaine who was too obsessed with preventing others from taking advantage/using her to realize he has been crushing her dearest dream all the time.

After the wakeup and before remembering: Most of her memories are gone and she is back to the Asseylum before the assassination. She does seem to slightly remember Inaho and Slaine is quite unhappy about this

After remembering everything: Her potential love for Slaine has fallen apart, the time with Saazbaum has changed him beyond recognition, instead of working towards restoring the peace he actively pushes towards crushing the terrans and intends to just push his own retarded ideals on her and marry her behind her back. To Asseylum that was one hell of a betrayal. The person she trusted so much suddenly pulled something like that.

So currently the only known candidate who has a shot at becoming her husband (and later on, emperor of Vers) would be Kaizuka Inaho, provided that his eye won't kill him before the war ends.