one being that severance of fea and hroa is 'unnatural' and is contrary to the original design, in the marring of
Arda.
A very difficult subject and question.
Forgive an old Ent for seeking clarification.... I'd like to understand this sentence.
You say "in the marring of Arda."
Do you rather mean "due to the marring of Arda" perhaps?
(In the end this differential may not matter to your question, but
the one implies a 'resultant' effect of the marring, while the other implies a 'causative' application during the marring's occurrence.)
The pondering here is difficult; certainly not 'clarified' by
Tolkien anywhere I know of personally.
(Which is not exhaustive, though often exhausting!)
The Children were completely unknown to the
Ainur during the Three Themes, being entirely
Eru's creation.
The Ainur were never authorized to '
adorn' the existence or being of the Children by Eru. So the likelihood they could 'touch them' in any way 'causatively' is almost certainly 'out of the picture'.
And, if indeed their
spirits are not bound to Arda,
Melkor marred Arda at two points... though they are essentially the same point, just expressed within two different 'times'. First, during the Music, and later physically. Yet if the spirits and Arda are not connected, the one has no impact on the other.
If I had to make a 'decision' based on current knowledge and thought, it would be it was Eru's plan from the beginning.
I refer now to this from
Ainulindale:
"Then
Ilúvatar spoke, and he said: ‘Mighty are the Ainur, and mightiest among them is Melkor; but that he may know, and all the Ainur, that I am Ilúvatar, those things that ye have sung, I will show them forth, that ye may see what ye have done. And thou, Melkor, shalt see that
no theme may be played that hath not its uttermost source in me, nor can any alter the music in my despite." For he that attempteth this
shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined.’
This is followed by:
‘Behold your Music! This is your minstrelsy; and each of you shall find contained herein, amid the design that I set before you, all those things which it may seem that he himself devised or added. And thou, Melkor, wilt discover all the secret thoughts of thy mind, and wilt perceive that they are but a part of the whole and tributary to its glory.’
Especially this mention "
all the secret thoughts of thy mind," since he was clueless about the existence of the Firstborn and the Followers (the Children) means he had nothing to do with them and their being.
Thus what Eru says is this: all Melkor did was foreknown... and Melkor was but an instrument in helping make it so. All is 'from the source' Eru Himself, and utterly planned for in the Themes.
And the key: none of it
actually exists as other than music (thought) until we hear Eru:
Therefore I say: Eä! Let these things Be!
In short:
1. I do not find anywhere a reliable source or even inference Melkor was 'causative' in the Severance. He was clueless about the Children during the Song.
2. I do not find anything firm suggesting a 'resultant' ('consequent' may be a better word choice) severance as Melkor sought to physically carry out his discordant objections during the singing.
3. I do not find anything firm suggesting Eru would have
added an 'unforeseen' later punishment to Man in his spiritual state, for his 'rebellion'. This too was foreknown.
ADDED NOTES:
If we bring in Tolkien's Catholic perspective, such a thing COULD be possible.
He may envision a 'death and reuniting' different than the Biblical one.
He would most likely hold the view Man, in his rebellion against
God, 'died spiritually' though he remained living in the flesh and with a 'soul,' later to be united.
Biblically, while this 'seems' a later event, and was 'spoken' by God at a later time, it was there also foreknown.
The Spiritual rebirth within man, in a sense, 'reunites' the dead spirit again with the living flesh... though the spirit of man was never really 'gone'... simply 'dead' and without ability to have any effect on man. Somewhat different than his Eru
events, but very similar.
As Tolkien wanted no 'overt' references to Christianity in his work, this could well be why it is not made clearer.
All that said, Melkor, like Satan, was not the 'cause' of the death of the spirit of man...though he was a tool helping bring it about. It was man's own
CHOICE bringing his destruction.
Yet Eru foreknew this as well, and made every provision for it from the beginning.
There are, of course, also massive
differences between Tolkien's 'creation story' and its specifics, and the Biblical 'creation story' and its specifics. But Tolkien states while there should be no "overt Christianity" in Myth and Fantasy, the
elements of Religion and Morality MUST be there. (My additive: The only difference between
authors and how they play out being each author's own background, desire and intent.)
I don't know if any of this rambling helps.
(but I'm always happy to ramble nonetheless. 😁)
I'll keep pondering this issue... it's an interesting question.