'Good Often Does Evil'

[Ent]

Bit of "word" clarification is needed here.

Don't tell anyone, but Ent must agree with you here, Deimos.
Tolkien KNEW the word, not just knew the word.
Sam is the epitome of jealousy as Frodo increasingly looks to - even leans on - Gollum.
Tolkien puts Sam's rigid, opinionated outlook on things on display in several ways - Sam has difficulty moving beyond his set opinions to perspectives.
Loyal to a fault - and sometimes the fault gets in the way.
If Sam were given his way with Gollum, the quest would have failed.
Providence, working through the things that are, spared the quest from many things - including Sam at times. The same loyalty that was a weakness was also a strength, as it made him listen to Frodo in spite of himself and kept him from carrying out his destructive wishes toward Gollum and, ultimately, the Quest.