I have a semi-regular get together with a handful of guys from my old addictions recovery meeting. Very informal - we just hang out for a few coffees at a Tim Hortons some Saturday or Sunday mornings.
Here's my point: if you indicate by the group email that you are going to be there but then you miss it, it is not necessary to apologize. Or okay, maybe some sort of acknowledge of the situation makes sense and that might come out in the form of an apology. I don't need it or look for it but I guess it's something people might do.
But it is not necessary to phone me and repeatedly apologize and then send me a follow-up email 3 days later with yet another apology. If you were supposed to give me some money you owe me or something like that, then sure. An apology makes sense. But it is just some informal gabbing over coffee. You are not there for me.
If you are imagining your absence left me in tears --> no. If you are imagining I got all specially dressed up for you --> no. I just assumed something had happened and maybe I'll see you next time. Good enough. It's not that I don't care about you but WE ARE MEN.