and then occasionally this happens

You meet an old friend, someone you used to spend time with, not a lot, but pleasant, always. For years it has only been the odd Xmas card or email but now it's face to face, nice. Why did we lose touch again? We laugh in disbelief. We talk but of course, the music is too loud, too many people and you only stay for a short while. 

The next day, you get a long and delightful email including an invitation to a garden party. 

Lovely. 

Only, you cannot go because right now you are exhausted and you know from experience that you cannot push your luck, that you need a couple of days rest. 

So you reply with your usual jolly mix of banter and regret and sort of by the way you mention that since the last time you met all those years ago, you have acquired this chronic illness. (In a footnote, you provide a link to a site explaining in basic terms what autoimmune vasculitis is.) And before you send it off, you invite him to come round to your place instead, one day soon, to sit in the garden, maybe, with a glass of wine, before the winter?

Within the hour he replies. He lists his pressing commitments in the weeks and months and years to come. Sorry.

I delete his reply. 

This has happened before. More than once. I am no longer mad and I, no, I don't think these were the wrong kind of friends either. I know it can be awkward, not everybody has a patient heart of gold. And don't come and make me feel I need charity or, worse, pity.