Foul-weather friend

The Urban dictionary suggests the meaning as :

The opposite of a fair-weather friend, a foul-weather friend only seeks you out if they have a problem, need a shoulder to cry on, a ride to town or someone to watch their dog, but otherwise they act as if they don't even know you. They're only your chum when they're glum.

A foul-weather friend will never call you to go out with other friends, go to a show or just go hang out, but the minute trouble comes, your foul-weather friend knows you are good old reliable you, the one who will listen when no one else will, and they act like you're their only friend. Don't expect the same in return either. When you've got a problem, they'll usually tell you not to bring them down.

Yooooooooo I find how to describe one of my cousin's , I said to myself ...yup this suits him . Whole of our family describes him so but hardly knew there is a word for such people too. Unfortunately we all meet such people at least once in our life. They deserve to be known as something and they do. The best characteristics of such people is they become predictable and later you have to do nothing but to somehow ignore them or if not possible then face them . Well what kind of inherited qualities these people have to become so , i am not sure anything other than being mean in initial phase of life they become our foul weather friend , since they resemble mean-ness in all their acts they tend to behave like this .....isn't it going like a negative blog .......well shall i go ahead n describe such people or give solution to avoid such people or just mock about their behavior.

I ain't no GOD ...(is it, i can believe??) so lets go ahead....more adding to their characteristics is whenever in trouble they will be find you no matter which corner of the world you are in, and start pitting about their conditions .... and once it comes to their happy days no matter even if you are juggling in front of them they will ignore you. In their happy days you will find them sharing their happiness with everyone other than you and the moment of your sadness, you will find them with least possible time for you. Well you are most reliable for them and at the same time they are least reliable for you .
Of course they continue to haunt you with their deeds but then you have to carry the misery of friendship / relations to bear upon your shoulders.