Whoops i meant jealousy.
Man am i bad at this. LOL

Do you mean specifically in a relationship, or jealousy in general?

Both you decide, give me your opinion on both if you want.

GUILTY! sincere feelings LOL i jsut put that one up to see who actually thought that... i guess some of us here on fanpop do.
I disagree with that one one hundred percent, i mean if you really "Love" the person i mean come on give them some space, do you doubt your parner that much?
Thats were GUILT kicks in is are you afraid of them betraying you? I mean jealousy can only be attained when you know you've done something wrong throughout your relationship; you are only afraid to be found out therefore you keep your partner in check to try and turn the tables on them.
Incecurities fall under guilt as well you are afraid of the person leaving you because of what you are uncomfortable with. Therefore you feel guilty, by blaming yourself for your "flaws"

I think sincere feelings stem from insecurities as well. In general it all boils down to being unsure of yourself. I would know.

It all comes down to competitiveness for me...

When I get jealous, it's not because I doubt their love or are actually afraid of losing them, and I don't really get the guilt choice, I haven't done anything so far to be guilty of, really...

But it's competition. I see the girl he's checking out/previously dated/whatever, and I go over them in such minute detail, saying oh I'm better in this way, but they're better in that way, they do that better, but I do this better...are they skinnier than me? smarter? funnier? cuter? ...lol I torture myself over everything, because I want to be the BEST. For him. And then I get over it after a couple days. :)

Its about comparing yourself.

Mainly due to something one believes he/she is lacking, and other minor yet present catalysts..

Depends on the what the jealousy is about. Someone isn't going to be jealous over a test score for the same reason they'd be jealous over seeing an ex with a new person. They aren't going to be jealous of the way a person looks for the same reason they'd be jealous of someone winning the lottery.

Whenever I'm jealous about anything, I hardly think about myself. It's more of "Why are you in this situation?" than "Why aren't I in that situation?"

I'm only speaking for myself, though, because I think jealousy is a complicated emotion that behaves different for everyone.