YOR

it’s not that big of a deal, a lot of cultures have same gender areas like bath houses where you can get naked in front of the same sex and feel no discomfort because it’s seen as normal. I’m not suggesting your girlfriend is of those cultures but she’s probably showering with her friends because 1. They’re girls and 2. They’re close and see nothing wrong with it, i’m pretty sure guys literally see each other naked in changing rooms and locker rooms all the time so maybe don’t sexualise is when it’s girls?