There's an obvious answer here ... becoming an orphan in September. Dad (and Mum) were friends, as well as parents. Although I know they are in Heaven and I will see them again, it's sad not to be able to chat to them, see them, give them a hug (and get a hug back).
The other thing that made me sad is that I still find it impossible to cry for them. I often have found that I find it impossible to cry for my major losses ... but that makes me sad.