No, the person like that is mentally ill if it is too much and she/he should seek a doctor because it's too dangerous..Why?
I have a friend who had a bf who is so very possessive and jealous it gets worst when he is angry cos of jealousy he cannot control anymore with his feelings and would end up hurting my friend physically that's too bad. My friend was so afraid because her bf is not doing a normal attitude towards being possessive and jealous and they always argue because of that.
So I advised you to not let your emotions rule you just control. ask your self why you are like that? what is the reason? if your answer is not normal then I think there is something wrong with you. I hope you won't get me wrong since I example my friend with his bf.
Jealousy is normal but too much of it is not good.