I think the biggest thing I miss is the intimacy.

I just miss knowing you'll be there when I get back, or that you'll be round soon enough. I miss waking up in the middle of the night and seeing you there, whether you're turned away from me or not. I miss being able to cuddle, whenever at all. I miss knowing I'll have the company in most things I decide to do. 

I just miss having someone be close to me so much of the time.