At 58, I'm a bit older than most of you guys going through this but I also never remember having the same feelings when I was younger. I've thought from time to time if there was something that happened years ago that I could call a MLC but I don't think I actually went through one. Reading through the thread, I think the biggest difference is that we never had kids. A lot of you seem to be at the point where your usefulness as parents is waning and leaving you with these feelings. I could be off on that.
We're married almost 30 years and happier than we've ever been. I haven't felt the need for a group of guys to hang with for a long time. As someone mentioned earlier about group vacations...that seems like a nightmare. I couldn't imagine going on vacation with even another couple much less multiple couples. Maybe we just never really clicked with another couple. We prefer to be left alone and we kinda wing it a lot on vacations. Not that we're not good in a group setting as we have no issues at parties with friends, family or neighbors.
I guess a big thing is that I'm never bored. My bigger fear is that I'm running out of time to do all the things I want to do or learn all the things I want to learn. Time is going too fast!
I still feel like a kid and enjoy every day. I don't take the good times and good health for granted. Don't let another 10 years pass before you find those things that make life worth living!
This could be my wife and I. No kids, I'm 56 (her 60), we have friends but not the every-year vacation type. Most of our friends are back in NY (we moved to NC 2 years ago). We have taken a few trips with other couples and it's always been less than we thought it would be - it's waaaay better with just her and I.
We're probably tough to be friends with because we're perfectly fine seeing people every so often and leaving it at that. Even with our best friends, it's like "that was a great dinner / evening out together... see you in a month or so!" We do like to do things and like you mentioned, are fine at the party / neighborhood thing / get together / whatever. But overall, we're quick to get exhausted by people. For every weekend we do something with others, we need two weekends alone to recharge.
I don't think I've had an inkling of a MLC - a lot of things posted here I just don't relate to. I do think the no-kids thing might be part of it. It's just a completely different lifestyle.