You are exactly correct about polyamory. It takes a lot of openness and good communication skills to navigate relationships that have no built in rules. And sex may or may not be a big factor in those relationships. I have a partner who lives on the other side of the country from me just now. It’s certainly not one big orgy, although I did just write something the other day about weird things young men say to me about sex (I’m middle-aged — so you are definitely not over the hill at 29 or 30!)
You sound like a very sensible, grounded human being. So glad that you’ve found an awesome partner and can now look back with laughter at these other guys!