i wonder that too
See,when you are in a relationship,you become blind,you can't see what is "Obvious" to everyone else. "They don't want to be bother,when they alienate you"! When a man is in love with you, he make time for you,he can't get enough of "You"!
they no longer want to be in a relationship with you but don't have the guts to just tell you.. they are hiding something from you.. they simply need space, maybe they feel the relationship is moving too quickly or that you are smothering them..