Human beings are like doors, some of them are open, some others are closed. Some of them take you to good places in life, some others take you somewhere different. Some are easy to open, some others never open no matter how much you try. There's a new opportunity behind every closed door, behind every person you meet. You have to be wise and choose which door to carefully open, which person you intend to trust. Not all doors will take you somewhere good. Not all people will keep their promises. 

And in the end, you need to always know when it's time to leave and close the door behind you. Not everyone deserve your presence.