I am going to say communication. I refer to honest real life communication as an LDR or internet based relationship is entirely different. In these you don't see the body language or non verbal communication which are the cues you need as part of what I would call the real thing. LDR and internet based communications can too easily be manipulated. You need to be able to communicate face to face. This is critical. In my opinion until this takes place you shouldn't be making any kind of commitment.