His Friend Pees With The Door Open

My boyfriend has this friend he grew up with. They literally grew up together. His mom ended up becoming her foster mom for years. She was never adopted because her bio mom refused to sign her rights away. They are obviously really close and it does make me feel weird when I text him and ask what he's doing and he said she's at his at or he's at hers. I'm trying really hard to build trust. I was over there today and she told the both of us she was going to the bathroom. I found it weird she felt the need to announce that while we were just at his house. He told me not to go into the hallway because she leaves the bathroom door open when she uses that bathroom. I asked why and that's weird and he says "It's personal. She doesn't like small spaces or feeling like she's trapped". That makes no sense to me because if you're in the bathroom, you're obviously not trapped. I went home early because of stuff with my roommate but it just makes me feel weird she using the bathroom with the door open in my boyfriends house. Am I overreacting.

From what he told me she will literally piss herself before using a public bathroom. She doesn't close her bedroom door, and I'm not sure how cars. I notice whenever they ride in a car he has the window rolled down and she will literally have her hand gripping the outside of the window and won't talk. She will just close her eyes until we are out if the car. I thought maybe I could ask her why she had this fear but idk if that would be over stepping since we aren't close.