What would we call a man who is always suspecting, distrustful and worried about his wife being wooed by other men? He considers his wife naive and the world (other men) as predators in waiting.
It would definitely have negative meanings since the wife is just the opposite, i.e. she is unsuspecting.
"Insecure" is a pretty accurate word. Being insecure about your relationship can mean you are constantly worried and suspicious that your partner is attracted or involved with someone else. Bear in mind that insecurity has a wider application and can go beyond a mistrusting feeling in a relationship(see below).
Another accurate example would be "Jealous".
However, jealousy is a much more temporary condition/feeling often caused by insecurity, which is a long term (and more concerning) personality trait. All men can experience jealousy, but insecure men are affected more frequently and severely.
Protective might be a good word:
1.1 Having or showing a strong wish to protect someone or something:
From the Verb form protect:
Keep safe from harm or injury:
If you wish to stress the fact that his primary mistrust is toward men, who might use her unsuspecting naivete to harm her, this would be a good choice as the etymology implies placing himself in front of his wife, between her and those who would take advantage of her:
mid-15c., from Latin protectus, past participle of protegere "to protect, cover in front" (see protection). International economics sense from 1789. Related: Protected; protecting.
protection (n.) Look up protection at Dictionary.com mid-14c., "shelter, defense; keeping, guardianship;" late 14c. as "that which protects," from Old French proteccion "protection, shield" (12c.) and directly from Late Latin protectionem (nominative protectio) "a covering over," noun of action from past participle stem of protegere "protect, cover in front," from pro- "in front" + tegere "to cover"
Over-protective projects the negative emotion more forcefully.
Jealous seems like a good descriptor for the more general feeling toward his wife. The etymology shows that the connotations of the word may be broader than our common usage:
c.1200, gelus, later jelus (early 14c.), "possessive and suspicious," originally in the context of sexuality or romance; in general use late 14c.;
also in a more positive sense, "fond, amorous, ardent," from c.1300, from Old French jalos "keen, zealous; avaricious; jealous" (12c., Modern French jaloux),
from Late Latin zelosus, from zelus "zeal," from Greek zelos, sometimes "jealousy," but more often in a good sense ("emulation, rivalry, zeal"). See zeal.
In biblical language (early 13c.) "tolerating no unfaithfulness." Most of the words for 'envy' ... had from the outset a hostile force, based on 'look at' (with malice), 'not love,' etc. Conversely, most of those which became distinctive terms for 'jealousy' were originally used also in a good sense, 'zeal, emulation.' [Buck, pp.1138-9]
Among the ways to express this in other tongues are Swedish svartsjuka, literally "black-sick," from phrase bara svarta strumpor "wear black stockings," also "be jealous." Danish skinsyg "jealous," literally "skin-sick," is from skind "hide, skin" said to be explained by Swedish dialectal expression fa skinn "receive a refusal in courtship."
The construction He's jealous of ... would tend to put more stress on the suspicious rivalry he feels toward the seduction of other men. Using He's jealous for ... might put more stress on the fond amorous zeal he feels toward her.
This is a man who fears (not feels)and he is a paranoid (TFD) person who suffers from paranoia, the unreasonable fear or irrational belief that other people are plotting to harm him or her.
http://www.thefreedictionary.com
anxious:
This is the defining characteristic of Shakespeare's Othello (and his wife is also innocent and unsuspecting). If you said "an Othello type", in an appropriate context, it could convey what you need.
