It is Possible maybe he has some issues or something going on with commitment.Or he could be dealing with a illness, like everyone said we can't diagonose on here. But I wont rule out a mi , esp since you know him and were in the relationship , maybe there are signs we are unaware of. When this stuff happens you always hear maybe the person just didn't want to be with you , but sometimes underlying issues can be behind his behavoir but like you said you know him and we don't his patterns , I would wait it out and see I he comes back , if he does , it could very well be the depression or something more. Wishing you good luck!! I know the pain of not seeing or talking to your loved one as I am going through it myself.