One of the meanings of 'jealous' as mentioned on dictionary.com is:
- solicitous or vigilant in maintaining or guarding something: 'The American people are jealous of their freedom.'
Now, if a man looked and smiled at my wife I would become very jealous but if I described this and said: 'I'm jealous of my wife.' it would not reflect the situation or my feeling.
It would suggest that my wife has something that I want but don't have. Also, it may imply that my wife did something to make me jealous - which in the above situation never happened because it was the man that looked and smiled.
In Arabic there is a specific word and preposition to reflect these types of situations as opposed to the use of jealousy to mean wanting something someone else has, which in Arabic has yet another different word.
The above example from dictionary.com about Americans being jealous of their freedom does not leave any room for misunderstanding or multiple meanings because it is not possible to be jealous of an inanimate object (albeit an abstract one like 'freedom') but it is ambiguous when it comes to people like my example above, hence the possible misunderstanding and lack of accuracy in expression.