tolkiens legendarium - Why did Fëanor refuse to give even one of the Silmarils to Yavanna to revive the trees?

Right near the beginning Of the Flight of the Noldor:

Yavanna spoke before the Valar, saying: "The Light of the Trees has passed away, and lives now only in the Silmarils of Fëanor. Foresighted was he! Even for those who are mightiest under Ilúvatar there is some work that they may accomplish once, and once only. The Light of the Trees I brought into being, and within Eä I can do so never again. Yet had I but a little of that light I could recall life to the Trees, ere their roots decay; and then our hurt should be healed, and the malice of Melkor be confounded.'

Yavanna needed "but a little of that light" to revive Telperion and Laurelin, yet Fëanor refused to give the Silmarils up:

Then Manwë spoke and said: 'Hearest thou, Fëanor son of Finwë, the words of Yavanna? Wilt thou grant what she would ask?' There was long silence, but Fëanor answered no word. Then Tulkas cried: 'Speak, O Noldo, yea or nay! But who shall deny Yavanna? And did not the light of the Silmarils come from her work in the beginning?' But Aulë the Maker said: 'Be not hasty! We ask a greater thing than thou knowest. Let him have peace yet awhile.' But Fëanor spoke then, and cried bitterly: 'For the less even as for the greater there is some deed that he may accomplish but once only; and in that deed his heart shall rest. It may be that I can unlock my jewels, but never again shall I make their like; and if I must break them, I shall break my heart, and I shall be slain; first of all the Eldar in Aman.' 'Not the first,' said Mandos, but they did not understand his word; and again there was silence, while Fëanor brooded in the dark. It seemed to him that he was beset in a ring of enemies, and the words of Melkor returned to him, saying that the Silmarils were not safe, if the Valar would possess them. 'And is he not Vala as are they,' said his thought, 'and does he not understand their hearts? Yea, a thief shall reveal thieves!' Then he cried aloud: 'This thing I will not do of free will. But if the Valar will constrain me, then shall I know indeed that Melkor is of their kindred.' Then Mandos said: 'Thou hast spoken.'

Fëanor had three Silmarils. Why wouldn't he give just one?

• Was the real reason the mistrust Melkor helped engender?


• Was each one so dear that he was not willing to give any of them up?


• Was there too little light in just one? (But how would Fëanor know that?)


• Were the three (thought to be) linked?