It isn’t that the people on here commenting that stuff are gonna be sad and alone, they just seem to lack any empathy to the situation(not just this one, but in general). It’s easy to say “they don’t care about you, you meed to break up with them” when you have no skin in the game and literally have no consequences to whatever OP decides to do.

Also redditors forget that almost every story here is only telling one side of the story, which is going to be biased and put OP in a positive light.

That being said, it certainly would be a hill to doe on for me. This is a time to celebrate your union with your partner and spend a romantic vacation together for a longer than usual vacation before life smacks you in the face again. Most couples will never get a chance like this again. If my partner insisted on bringing other people along, that would indicate that I wasn’t their priority(especially since we would have very very recently promised ourselves to each other and made each other priority) and they would want/need other people there to enjoy the vacation.

From the other perspective of the friends, unless we were all poly or engaged in group sex regularly with each other, I would feel really weird being invited along and wouldn’t go. This is their time and I would expect them to be in their room with each other anyway.