I am traveling with a work friend and her friend in Europe and we are here for two weeks in very safe cities. If I leave to go sit for a bit in the evening alone the ring leader girl gets pissed. Today we are waiting at the train station with plenty of time and I said I’d like to go look at other food options and she says very matter of factly “I’m not splitting up anymore I’m done”. Which feels very controlling for me being an adult and us being in a safe area, also she is with another person and she also has my location. I need time alone or I get overwhelmed, not to do anything adventurous without them but even just to sit at a cafe alone in peace. They’re starting to get on my nerves being very loud Americans and rude, but I’m trying my best to find peace and keep the peace/not argue. One of the girls I’m with is very opinionated and demanding though, so I don’t know what the best approach is to both keep the peace and say that I need time alone?

Edit: Thank you all for your knowledgeable advice and sharing your experiences. I spoke to her and approached the situation calmly and it did not go very well. I stated a lot of the dialogue here- “I am introverted naturally and need time alone to recover. I paid for this trip as well and I want to enjoy myself fully” she responded by shouting that she had made the plan with the other girl originally and I just asked to tag along (this is not entirely true as her and I made the plans before her third friend agreed). She said that I was disrespecting her feelings and it I chose to leave her it would ruin her trip as she would spend the whole time worrying about me. She stated that she would never make plans with me again and we would not be friends, she said that I would be r*ped and drugged for going out alone. She also said that she had told me that she “didn’t want to separate.” This is true, and I will concede on that. But I didn’t realize how dire it was- she doesn’t want me to leave her eyesight whatsoever, even to get a bottle of water at a station on my own. She has the itinerary for the remaining days which does include a bus ride, ferry, trip to a smaller island, etc. she has the only keys provided to the Airbnb and I truly believe that she would not allow me back in or inform me on the other Airbnb information if we didn’t resolve things. I told her that I acknowledge her feelings and I understand and would need time for several moments to myself alone without her and would not drink alcohol (to avoid being roofied) and would not stray farther than 4-500 feet from the building. She was still angry but seemed happy that I was willing to bend to her will. Then I left and had a mimosa anyway for an hour. I sent her excessive information (pictures of my location, when I intend to be back, who I was speaking to, etc) today and she seemed content. I think the best way to handle this realistically to avoid an explosion is by doing that for a day or two and then taking the hour I indicate to her to myself for the rest of the 11 day period and going wherever I would like and doing what I want to do. I believe she needs the illusion of control more than the actual control. It is passive aggressive and deceitful but I’m afraid of missing my flight to America. It is a lot, but I think she will eventually realize how weird her request is. My parents didn’t ask for this much even when I was younger so it’s new to me. Again, thank you all for your input. I figured you would appreciate an update on the situation and of course I do appreciate any further advice or input!