Gfrktyl

In The Lord of the Rings: The Two Towers Sam binds Gollum's legs with Elven ropes and then Gollum starts to scream like he was being tortured. Also when he was given lembas to eat he didn't eat it and it seemed to taste horrible to him.

Why did it happen? He doesn't seem to be a total dark villain like Sauron and his minions. Gollum just has some serious lust for The One Ring.

Why couldn't he tolerate Elven things?

Aragorn (as Strider) speaking of the Black Riders

For the black horses can see, and the Riders can use men and other
creatures as spies, as we found at Bree. They themselves do not see
the world of light as we do, but our shapes cast shadows in their
minds, which only the noon sun destroys; and in the dark they perceive
many signs and forms that are hidden from us: then they are most to be
feared. And at all times they smell the blood of living things,
desiring and hating it. Senses, too, there are other than sight or
smell. We can feel their presence – It troubled our hearts, as soon as
we came here, and before we saw them; they feel ours more keenly

Middle-earth seems to have an extra dimension/astral plane/plane of existence, which is referenced a couple of times.

On this other plane, which overlays the "normal" reality, good and evil are physically manifest, you are light or you are dark, or of varying degrees of grey between.

The Ring has brought Gollum too far into the dark side of that realm, as it was doing to Frodo (emphasis mine) . . .

Gandalf moved his chair to the bedside, and took a good look at Frodo.
The colour had come back to his face, and his eyes were clear, and
fully awake and aware. He was smiling, and there seemed to be little
wrong with him. But to the wizard's eye there was a faint change just
a hint as it were of transparency, about him, and especially about the
left hand that lay outside upon the coverlet. 'Still that must be
expected,' said Gandalf to himself. 'He is not half through yet, and
to what he will come in the end not even Elrond can foretell. Not to
evil, I think. He may become like a glass filled with a clear light
for eyes to see that can

Here we see that the ring is also bringing Frodo into that other realm, if he had been captured by the Wraiths he would have become a thing like them (I can't find a quote for that at the minute), but now Gandalf thinks he will go to the light, but that the ring will have its effect on him "He may become like a glass filled with a clear light"

Some can see the other realm for eyes to see that can (such as the Elves that came from Valinor, the Maia and other spirits and/or beings of power), he would have become invisible to everyone else.

How does the ring do this? The "invisibility" the ring provides is done by it bringing the wearer into the other realm, the more you use it the less of you comes back from there, and more you are in it, and of it.

Gollum can't abide the touch of Elven things because he has been partially drawn into the dark side of that realm.

One of the footnotes in LotR (I think it's in Return of the King) states that Gollum's long association with the ring made him unable to bear the touch or feel of things that were Elvish and/or unfallen Valar craftwork.

As you will recall from reading the narrative, he also could not bear the light of the Yellow Face (his term for the Sun) and he was not terribly fond of the White Face (the moon) either. As we read in the Silmarillion, these were made by the Valar and contained the last remnants of the Two Trees.

Other things did not bother him; but as we read in other works, the matter of the world was diffused with Morgoth's essence, making it much more agreeable to someone whose spirit has been corrupted by the Ring.

In Middle Earth, all matter including people seems to be imbued with power to a greater or lesser degree. Some of that power is native to the material, but power can be added to specific bits. The rings are the most compact and portable examples of this. A medium-sized example would be the door deep inside Moria which Gandalf tried to enchant with a locking spell. Larger examples include the Old Forest where Bombadil had spread out his will to absorb the land and its inhabitants into something of a bubble, a nest, within which he is master.

Power seems to be neutral in its native state, but usually ends up flavoured either to good or evil by the actions of the person who added power to that object. Hence the palantir of Minas Tirith becoming permanently tainted by the power of Denethor in his last madness. Hence the Three Rings being coloured to the good side by their having been forged without Sauron's presence. Hence, of course, THE Ring receiving the ultimate colouration of evil by its having been forged by Sauron alone.

In terms of our world, think radioactivity. A thing not natively radioactive can become polluted by exposure. A person long exposed can become tainted as well.

Contrast Gollum with Merry. When Ugluk treated Merry's wound with Orc salve, Merry screamed in pain, yet suffered no lasting hurt from it. Indeed, it efficiently healed his wound, albeit leaving a scar. Merry took no lasting hurt from it because Merry, like Hobbits and Men in general, was natively nonmagical. And, unlike another hobbit, Merry hadn't been exposed to highly charged and polarised power for half a millennium. One suspects a natively magical Elf, especially one who had seen the Two Trees, would have taken far more agony and injury from Orc medicine. And vice versa.

When Gollum was grabbed and tied up by Faramir's nonmagical soldiers, Gollum chafed against the restraints and complained, but not more than any other bound person would. Quite a different reaction came when Gollum was bound with ropes which had been handwoven by Galadriel's folk. Those ropes were layered with Elven spells (e.g., to untie themselves when a good person wished the rope down). They had been imbued with power coloured to the good side. Gollum, having been coloured to the bad side by 500 years of exposure to The Ring, could not bear the touch of such material. The lembas was not imbued with much more power than would natively be in its ingredients and baking and wrapping, so Gollum was not stung to agony by that Elven food. But his tainted body received it as the opposite of nourishment. To him, neutral dust would have been tastier. Granted, Gollum was a picky eater overall. Recall his disgust at Sam ruining perfectly good raw meat by cooking it. But Gollum could at least digest food handled by magically near-neutral chefs.