retreat weekend

We went to our church's retreat weekend, at a retreat center we have been going to twice a year for more than 10 years. I got a call beforehand asking if I could help with registration, but I had an afternoon meeting and couldn't. I was really pleased when John volunteered that he could. But his involvement didn't continue. He went to the program the first evening and then refused to go again, saying it didn't work for him. I'm very sad about that because he says he wants to connect more with me and this was just the kind of thing I would like to share. If he got to meals first he sat down alone. He did go to a tea organized by a friend of his, but instead of sitting with the group he sat alone. I sat with him, though I had wanted to joint the group. Interestingly he said that after I left he sat with his friend and some other people joined them. Sometimes he isolates himself because he has trouble following conversations if there is any background noise. But he says he would rather be alone. I'm an introvert myself, but this isolation strikes me as a a dangerous direction.