Alone
There is an interesting flavor to being alone again. My attention is completely free and I notice more things, I also don't have to worry about more than my own safety. If I need to cross a busy road on my route that's fine as long as I'm safe.
But soon, after not more than three hours, I begin to miss the affection between us and it dawns on me that I'll miss this for more than three weeks and there's no real replacement for that.
The first part, being completely free and only responsible for myself, is familiar from my past.
The second part, missing the affection and intimacy, is rather new and exists only since I've known you.