The similarity of "envious" and "oblivious" is coincidental:

• envious is just envy + -ous, where envy is from Latin invidia "envy".
• oblivious is from Latin obliviosus, from oblivium "forgetfulness" + -osus "-ous".

Edit: changed the title from "previous" (ahead on the way) beacause I apparently forgot what pre- means lol

If anyone's wondering how this "magic e" nonsense happened in the first place:

In the Middle English period, short vowels in open syllables were lengthened, so /ha.tə/ became /haː.tə/. Then, the schwa was lost, thus /haːt/. Now, the only audible distinction between hat and hate was the vowel length, and so the on the end was reanalyzed as a length marker; words that never ended with an /ə/ like whit /hwiːt/ were respelled as white to show the vowel length.

With the Great Vowel Shift, hate shifted from /haːt/ to /heːt/, and in the last couple of centuries to /heɪt/. Now, final shows a mostly-consistent transformation of the preceding vowel, perfect for flummoxing second-language learners!

Yep! Surprising but true!

Alone is first attested as Middle English allone, and earlier as two words, all oon.

Lone comes from a later shortening of alone (Apheresis is the technical term).

Alone and one don't rhyme anymore because of the irregular change from /oːn/ to /wʊn/ in Late Middle to Early Modern English. See also only, which comes from one + -ly.

• rage comes from Old French rage, from Late Latin rabia, a regularization of Classical Latin rabies.
• lobby and lodge are both from Late Latin laubia, a loanword from Frankish laubija, meaning "arbour" or "shelter".
• sage (the plant) comes directly from its Latin name salvia. (As a sidenote, the psychedelic salvia is one of many salvia/sage species and is native to Mexico).
• rouge is from Latin rubeus ("red"), while ruby is from Latin rubinus. This means that while ruby and rouge are closely related, they're not a neat doublet like the others.
• The latter half of (sub)servient and sergeant are both from Latin servientem meaning "serving".

Other pairs include sapient/sage (meaning wisdom, as in sage advice) and cavity/cage (the latter from Latin cavea > *cavia).