You don't sound dull at all, you sounds really nice. The dullest people are those who just talk about themselves and think their own lives are more interesting than anyone else's!
As a pp said, it could be that you dropped into the role of 'organiser' and if you don't plan something, noone thinks to. I was part of a group where one person was the organiser. She appeared liked planning stuff, and she had a bit more time on her hands, so we let her get on with it. When she had children, and less time, she stopped planning things, understandably. It took the best part of a year (maybe longer) before I realised what had happened and suggested a night out. I felt so guilty when I realised, but we'd just fallen into roles and habits.
Another thing is your friends who fell out with each other - nothing to do with you, but you're an unfortunate victim of that circumstance.
I think also when you first retire, you re-appraise your life, and you're thinking about these things. People who are still at work are often just getting by with work / parenting / home stuff. They might be in exactly the same boat as you re friends, but they don't notice it as life is so full. They may have the same moment of realisation when they retire.
Volunteering is brilliant, on so many levels. It keeps you busy, so less time to dwell on things, it gives you purpose - you know you're appreciated and are making a difference, it makes you even more interesting - you have a passion you can talk about and share with others, you meet new people who might just become friends, or links to new friends.