Wait, is the wife jealous? Or the man.

In any case, one source of jealousy can be one's own unfaithfulness (or the wish to be unfaithful). Someone, who can't believe in the fealty of others and is jealous for no reason is usually him or herself not capable of jealousy and is pojecting his or her own failings onto the partner. And the egotism that others mentioned also fits in. Someone, who is jealous out of egotism will, out of the same egotism, also be willing to break promises and hurt others if it serves his or her whims.
Or in other words: someone, who is incapable of trusting others (without reason) is probably him- or herself not to be trusted.

all i want to know if will this game feature a madness mechanic that will allow me to unleash a rapmpage now and again..
and give me superpowers.

It seems like people already covered the scenarios I would imagine for a very severe case of jealousy.

Other not so extreme cases would include trying to manage a partner's social life; reprehending her for spending too much time with the opposite sex even if those are just friends or coworkers; forcing her to end these relationships because he thinks they're too important in her life and distract her from him. Threatening to end the relationship if she doesn't stop seeing them because that means they're more important than him.
Freaking out if she takes too long to reply to a text or call back;
Constantly checking up her phone and social networks;
Being suspicious of each and every man she talks to;

Gonna bump this one as it's more relevant now. The story I've been working has evolved into a game project with a friend of mine and I'll be making the script.

So, the OP still stands. Any pointers, ideas and suggestions are appreciated :)

There's actually a Chabrol movie on that subject, if you're interested.

Nicely done.

I would think that obsessive jealousy would make the man think about her nonstop, to the point where it interferes with his daily life. He would stalk her mail, emails, phone messages. He would play word games in order to catch her in lies. He would follow her and try to catch her doing something bad. In his mind she already is false as he can not believe that someone could love just him as he is unworthy and unlovable (his insecurity is driving this jealousy). If your story is going to go down that route you can also show how he falls deeper into the madness, letting his responsibilities at work and elsewhere slip as his obsession with his lover takes over. we read in papers everyday how that ends.

I think

and
are different categories. The former being tied to a sense of injustice (at your own expense in these exemples, but the same annoyance is felt when it happens to unrelated people) and the latter to mere selfishness (there is no justice/injustice at stake). Self-entitlement tends to blur the line between feelings of pure jealousy ("unfair" only in the eyes of the subject) and feelings of injustice (unfair whoever the subject is). Most people don't feel crippling envy because they distinguish both cases.

Unless, of course, it's mere jealousy of not-being-the-one-abusing-the-situation (not "wanting to get the benefits as entitled to" but "wanting to be the one who gets the benefits without being entitled"). Which occasionally hides underneath justice revendications... (less often than accusations of jealousy are rhetorically used to dismiss justice revendications, i must add, but that's another can of worms).

Jealousy is often strongly linked to a feeling of injustice, be it legit or not.

Jealousy is resentment and fear manifesting themselves as anger and a sense of entitlement.

Master Yoda said it best.

"Fear is the path to the dark side, I'm afraid. OH SHIT." *slaughters younglings*

Sounds boring. Does the story end with the man being cucked as his wife is sleeping with another man, so he pulls out a chainsaw and massacres them both in the bed? That wouldn't be boring.

That would be spoilers.

The first one is envy, the second one is jealousy. They are not both the same.

And jealousy is more about losing something - so whether it is husband/wife or friend it is about the feeling you will lose them to someone else not just the fact they are liked or even that you dont like the fact someone likes them.

So basically you are envious of what others have, and you are jealous about what might be taken from you.