Because the context has changed to exclusively God so whatever it is, it's not human jealously. Reverse translating it starting from English "jealous" and then superimposing this over God doesn't work because the English word jealous doesn't fit this unique context the Hebrew does. To start the word is better translated as "zealous".
Ancient Hebrew is an extremely concrete language and English an extremely abstract language so they don't really fit that well. The word in question is קנא (QNA) (vowels are formed by the addition of accents on the characters). All words have a 2 character root and the root in this word is קנ (QN). The 2 character root froms the meaning of the word. From there each character in ancient Hebrew is a pictograph that carries meaning, combining together they form concepts. The pictographs is from the characters QN. The N is a pictograph of a sun on the horizon also meaning the gathering of light. The Q is a pictograph of a seed. NOTE: modern Hebrew uses a the aramaic square script (what I've copied and pasted) where the pictographs are not clear, you need to look at a
Paleo Hebrew or Phoenician script to see the pictographs
So 2 letter root of QN has the abstract meaning of zealous and has the concrete meaning of a nest. The parent bird gathers materials to raise their seeds (eggs) in. So zealous here is a passionate devotion towards its own.
The child word QNA adds the pictograph of an ox with abstract meaning of strength (so it's like adding to the meaning as a strong nest). Together the word is formed under the concept of a parent bird will guard over and protect the nest and eggs from predators. Man can guard over the family, wife, possessions in a positive way (protect, from an enemy) or in a negative way (by not trusting or a desire to have anothers possessions).
This forms the meaning of the word in Hebrew where in English there is an probably a concrete etomology to the word but in practise the word is an abstract and has no concrete connections with it and we just associate a very specific action/feeling over it. In Hebrew there is a lot of information that gives meaning to the word that we loose when we just superimpose an English word over it that only study will reveal.
The NT word is in Greek which is also an abstract language (or more abstract than Hebrew) and to get to its meaning you will have to study the Greek to see if the English covers the meaning well. I just expanded the Hebrew to show that it's more than what we associate with in the English even if the translation still is appropriate.
