Either way, the Hittite prince is in for a world of trouble... For the Egyptians to accept him he would basically have to cease to be Hittite, fully adopting Egyptian cultural mores in the process... And that's assuming they even give him the chance to do that - the entire Egyptian government would be opposed to him.
Ankhesenamun, as Kaiphranos pointed out, had no real power base. Her only value was in that she could legitimize a lowborn pretender (Egyptian kings were legitimized in part by the lineage of their queens in certain circumstances, and the post-Tutankhamun certainly met those criteria), and that value wasn't even exclusive to her (Horemheb ultimately legitimized himself by marrying Mutbenret/Mutnedjmet, Ankhesenamun's aunt and Nefertiti's sister). The only way her marriage to a foreigner could go through is if she was a powerful ruler in her own right, with a sufficient enough power base to tell large parts of the Egyptian court to sit down and shut up.
BUT, that creates a further catch: If she's powerful enough to do the above, that essentially eliminates the need for a foreign husband. If she has an adequate power base, she can rule as a rare female pharaoh in her own right, and the marriage to the Hittite prince is rendered superfluous.