Nahh this is just wrong. The trope of sending an older bride to marry a much younger (child) groom from foreign countries who eventually get together when the groom is of age is not a unique trope. So many manga (both straight and homosexual) have already explored that trope.
So I dont agree with you when you say that it is nearly identical. Besides, so far these are the only similarities of the two stories:
1. Older bride and younger groom
2. Gets separated bc of power struggle in the groom's country.
3. Uke has no idea what happened to groom until the groom returns when he's already grown up.
That's it. Besides shuraka reappeared when he has already won the emperor seat. whereas in Palace Of Omega, the seme reappeared when he has still yet to win the emperor seat.
And dont get me started on the stark differences of the two ukes. Not only in body built but as well on what they did during the semes disappearance.
Basically, there's already a shit-ton of difference between the two stories! Any similarities you see are just common tropes.

I am sorry but the story is like nearly identical to palace of the omega T.T kinda icky. I love palace of the omega and so this stinks a bit. Especially because the OG Manga does it so much better. It’s unfortunately very short