TL;DR I organize a social event within a group of friends. One of them cannot come for medical reasons. Can I do anything to comfort him?
We are a group of about 30 people aged 19--40 who got to know each other at a 2-week scout meeting. We got really close to each other during this and try to meet regularly. Three of these live in a city quite far from me (3 hours by train).
I saw there's a concert of a band I like in their city, so I started a Facebook group chat with me and the 3 of them. Two confirmed and we planned the details (still in the chat), while one ("Joe") told us immediately that unfortunately he'll be in hospital at that time, and it was basically his only message, though he's not left the group chat.
I don't have any signal from Joe that he is uneasy with the situation, but I believe that he might be. Is there a way how to approach this in order to find out whether he's OK with all of this? My ultimate goal is that this does not leave any scars on our friendship (and I may be overthinking this and there's nothing bad going on).