Why does my boyfriend always kiss me "good bye" but not "hello"?

Don't think too much on this :) It has just become a habit of his I'm sure. A lot of people do this because they will miss their significant other and steal a hug or kiss before they leave, however when greeting wheres the need? you are right there haha.. If you want him to do this though then don't make a big deal out of it. Just make the first move, hug and kiss him when you see him first and he may eventually do the same. It also makes the other person feel like they were missed :)