Essentially, the Jedi philosophy is Buddahism.
The Buddah says that any/all attachment, to people things whatever, is the cause of all suffering. People suffer because they do not want to let go of their attachments to whatever. The only way one can reach enlightenment is to be free of all attachment. No lovers, friends, possessions.
The problem with Jedi is they want to be good. Good is the result of attachment. Which is why "good" jedi fall to the dark side. Passion. Their passion for life (what they are attached to) causes suffering in them and they fall to the dark side.
Yoda said over and over in the movies that a true jedi must let go of all attachment in order to serve the force properly (specifically when counciling Anakin). He warned Anakin if he didn't let go of those he loved he would cause suffering and fall to the dark side. He further counciled Luke later on that suffering, fear, attachment lead to the dark side.
A real follower of the Jedi philosophy would hold no attachment to anything. Be completly passive and unemotional. The danger here is arrogance. As you loose emotions you loose perspective and become logical/intellectual. This leads you to arrogance which Palpatine used against the Jedi.
A true jedi must not posses any thing they would ever fear loosing. Even friendship.A true Jedi must always be mindful of any attachment. Attachment leads to fear and suffering. The dark side are they.
This but i like to point out that friendship is possibol without the fear of losing it.