My story won't make sense because it's sort of complicated, but it falls under the category of Going With the Wrong People. Let it suffice to say that I shouldn't have let someone invite herself along, but I was too polite to open my mouth. Never again.
Oy vey, the things you learn about people when you travel together! Things about how often they shower or don't after spending the whole day in the hot FL sun ... things about how they insist on following you around even though you hate coasters & they love them, even though you eat on the go & they want a 3-course meal, even though you can't be bothered stopping for character photos & she wants to get photos AND autographs. (She's 23.) It was constant pouting by someone. It's funny how the oddest things need to click, like whether some people like a big breakfast & some people can just manage morning coffee.
My best advice is never be apologetic about splitting up. At the very least, it'll give you all something to talk about when you get together for dinner or whatever.