I’m a 42M, my wife is 37. We’ve got a great marriage, super happy, everything’s solid. About a year ago, we met this guy (36M) through some mutual friends, and over time he’s become really close to us. We hang out all the time, meals, weekends, trips, you name it. Lately there have been some running jokes about how we’re basically a throuple already, and those jokes have been getting a little more… not-jokey. For the record, I’m not into guys and neither is he. But honestly, the idea is kind of exciting in a weird way, and I really like having him around, he feels like a best friend at this point. My wife’s also open to it. So yeah… would it be totally nuts to actually explore this?
Exactly this. It can absolutely be a fulfilling relationship, but it takes significantly more work than being a pair does.
It also isn’t a good fit for everyone. You have to be not only extremely confident in the existing relationship, but also secure enough in yourself to understand that your partners are going to have independent relationships with each other just like you have an independent relationship with each of them. A lot of people just struggle with that.
Personally I find it to be a very rewarding experience, but I full expect that to not be the case for most.
If it is something OP decides to engage with I would definitely recommend lots of reading on poly relationships, seeing a relationship counselor who specializes in open \ poly relationships, and visiting poly forums to talk about the potential pitfalls \rewards.