OS -
IMHO, jealousy stems from one of two places. It either comes from within, or because of being without.
When I say it comes from within, it is because there are some people whose self-esteem is so low, that they do not feel worthy of love. So when they see the object of their affection merely walking past a member of the opposite sex, they feel jealous because they are absolutely SURE that the object of their affection would much prefer to be with the perfect stranger, whom the object of affection hasn't even given a second thought to. In this case, the jelousy is contrived within, and has no basis other than in the mind of the individual who is experiencing it. In my humble and loving opinion, this is unjustified jealousy (at least towards the other person) because the the object of one's affection is doing nothing wrong. Does it still feel real? Of course it does! But the only person that can control the emotion in this instance is the one who does not feed themself enough love to fend off the "green-eyed monster" and they need to make a decision as to how to rectify that without harming the relationship.
When I say it comes from being without, I mean that there are times when two people are in a relationship, yet one member continually exhibits behavior which is inconsistent with being in a relationship. For example, the person could say, "I love you more than I've ever loved anyone else in my whole life," and yet never do anything to demonstrate that they actually feel this way (which is what I call "being without"). And then to add fuel to the fire, the very next day after professing their undying love, perhaps you find them out flirting outrageously with someone else right in front of you! In this scenario, no matter how much self-esteem both parties to the relationship may have, the incongruency is the catalyst for the feelings of jealousy. And again, strictly IMHO, this is justifiable jealousy. This jealousy comes from "without". There is something wrong with the relationship as a whole, and it is normal to feel jealousy in this case. Of course, at this time, it is going to be up to the person feeling the jealousy to decide whether the relationship is worth holding onto or not, and different people are going to make different decisions on how to best handle it.
OS, as I've said to you before, the things you are going through in your life are causing you to think about these things. I am encouraging you to seek help - because you have the most unbelievable potential of darn near any young person I've come across. Please make the decision to do this, so you don't have to worry unnecessarily about things like this. You are too young to think about these things, and you have your whole life ahead of you to get yourself to the place you need to be to get past this! Please, get someone to help it along because you are worth it!
Your Friend,
growedup
.