To put it blunt it's the way people are. Especially if its your friend or something they might feel betrayed that you were talking to someone they like and you know it. They also might be too shy to talk to him/her and if someone talks to them they'll get jelous that they can't do that. Depending on the person theres different reasons to why they don't say anything about it. If she/hes shy she/hes shy. She might also not want to bother the person. Or they want to get back at the person behind their back.
Tell that jealous person that if they really liked you then they would only want you to be happy, and that your girlfriend makes you happy.
they are trying to get someone jealous or the friend asked them out and they didn't wanna hurt that friend's feelings (basicaly they thought of their bf/gf as a friend still)
If you are with someone else then it really should not matter what your ex thinks either way. If you are trying to make him jealous and just using someone to do so that is wrong and not fair to that person. If your ex is jealous you will know by the way he treats you.
Controlling
It really all depends on the person, and there feelings.
He's jealous and he's using the classic date someone else to get a person jealous method
you really cant do anything..why be with someone who wont let you be comfortable around friends or acknowledge the fact his got you and others want you
yes. yes it is, if you really love someone, you'll do anything to be with the person.
no, he bad person
Either talk to the person or ignore it and have more self confidence =]]
It's not really good to try to get someone jealous. It could backfire really bad on you...trust me. But it depends on who you wanna get jealous...if its a boy/girl then just pay no mind to him/her but pay attention to some of his/her closest friends. =]]
someone can be mean by really anything